I don't understand why you're even making this statement, no philosophical skeptic would disagree with this. Skepticism has always attacked our understanding of reality, not reality itself.
If anything it is the idealists, like Leibniz that argue that "reality is only in our minds", verging on solipsism. You seem to be misunderstanding Hume who more so points out that the only thing we can really "know" is our inner experience of reality, which is a bit closer to what you're arguing.
And the idea that there's an "inner experience" which is the object of our knowledge is the premise of idealism.
The objects of our knowledge are the world, directly.
When I open my eyes and see a flower, I see a flower. I don't see my seeing of a flower; nor do I see my inner experience of a flower --- where indeed, is the eye which sees inner experiences? And which eye sees that one?
This premise is the dogma of scepticism. Weighed against everything else it comes out vastly improbable.
When I see a flower, the object of my seeing (and my knowing) is the flower. My knowledge consists in having the experience of the flower, as caused by the flower. Without much scientific knowledge I do not know, indeed, that I am having an experience of a flower.
This talk of "having experiences" is a post-theoretical description of an event which is much more primitive. A dog which sees a flower knows there's a flower in front of it. It knows basically nothing about what kind of experience its having.
The dog succeeds in being oriented to the world as it is; the dog succeeds in knowing. As do we.
Neither of us are oriented towards ourselves. We are not peering inside our heads. Such muddles are the religion of scepticism.
Then you must have a fundamentally different qualitative experience of consciousness than I do.
The flower I am holding right now, it is real to me because I can observe myself experiencing it, however the flower you are holding I cannot experience because I am not observing your experience of observing the flower.
It is quite remarkable that you can experience that flower that I am holding and say that it's real while I cannot do the same for the flower you are holding.
> "A dog which sees a flower knows there's a flower"
I certainly don't know enough about the state of my dogs mind to know that my dog is seeing a flower, as opposed to say, merely experiencing clustered sensations in the same location as I am seeing a flower. I've looked at a flower and seen my dog eat it, so I have a suspicion that he recognizes something there, but only because my beliefs about how his actions might correlate with seeing something.
I also have friends who have seen a purple flower in the exact space I am looking where I cannot see a purple flower. What is the explanation for this?
> it is real to me because I can observe myself experiencing it
There is no such thing as "real to me". You are observing a flower. Seeing that flower means having a visual perception caused by that flower. That visual perception presents your knowledge (indeed, is) your knowledge that there is a flower.
When I look at you holding a flower I see the flower and I see you holding it. There's no mystery here. The objects of my seeing are things in the world. There is no 'private world'.
> I certainly don't know enough about the state of my dogs mind
What you 'know enough' to say is irrelevant. The proposition that the dog is seeing a flower is true regardless of what you do, or do not know. Knowledge models reality --- reality doesn't model knowledge. The proposition is true; your theory of knowledge should be revised to account for it.
> I also have friends who have seen a purple flower
The presentation of knowledge we call a visual perception, uses the mechanism of presentation we call 'my visual system' (which includes what I have learned to see). Just as a mountain is presented by different cameras, with different lenses, in different perspectives.
Insofar as I make linguistic utterances based on this presentation I'm engaged in theorising about the causal origins of my perception. Here mistakes are possible, but quite uncommon. If we think the stick is bent, we need only take it out of water to realise that the prior visual perception was caused by the refraction of light.
In this manner we learn what the causal origins of our perceptions are; and hence, rarely make mistakes.
Visual systems may be better at recognising some features of the world than others -- some cameras have zoom lenses. Likewise some may be broken. How your visual system presents your knowledge via seeing is arbitrary (water color, pastel, chalk...). Its built only to ensure that you can reliably infer its causal origin (ie., properties of the world).
But this theorising is irrevelant to what's going on. The propositions, "i know there is a flower", "there is a flower", "i am seeing a flower directly" etc. are all true. Our ability to give a linguistic account of the causal origin of this knowledge is fallible, but reality isnt.
I don't understand why you're even making this statement, no philosophical skeptic would disagree with this. Skepticism has always attacked our understanding of reality, not reality itself.
If anything it is the idealists, like Leibniz that argue that "reality is only in our minds", verging on solipsism. You seem to be misunderstanding Hume who more so points out that the only thing we can really "know" is our inner experience of reality, which is a bit closer to what you're arguing.