but are satellite launches a growing market? there is only so much space up there. Mars is a different beast, but that's quite a few decades ahead before it starts bringing "cash flow"
How do you expect to compete with fully reusable boosters a la SpaceX? Are you building your own and when do you hope to have them delivering paying payloads? Or does ULA hope to buy reusable rockets from Blue Origin, not just engines?
Nope, five of the eight ULA launches in 2018 were Atlas V's and Atlas V first stages currently use Russian RD-180 engines. ULA is interested in replacing those engines with Blue Origin engines, or replacing the Atlas V with the Vulcan (probably also using Blue Origin engines), but that hasn't happened yet.
His example was just one of many problems solved by putting stuff in space. The modern world would have a very hard time operating at the current scale of humanity without sats. Flight ops, shipping ops, transit navigation and routing for the stuff that you buy, general communication links you probably don't even know you're using when you are using them.
Slack is obviously very useful, but it's also trivially replaced. The ability to put stuff in space is not easily replaced. Conquering the inherit business risk of space operations and engineering when others won't is part the value of space companies.
Slack could be meaningfully replaced at a company with a git repo checkout and some local hardware.
Did you check today's weather forecast specific to your location?
Compared to what the 2,000 active satellites enable, Slack is just chatter.