Bitcoin is not anonymous. Should one be able to link a wallet to a real name (like, for example, phil21), they can then follow each transaction that wallet makes, and where every coin ends up.
Once you know phil21's wallet is empty, those looking to heist anything would look through which wallets the coins ended up in, and start linking identities to those wallets.
If a criminal knows to look, they see the risk no longer matches the reward. If they don't know to look, odds are they weren't involved enough to have followed phil21's coins and wallet back to a street address in the first place.
Sure, the risk isn't zero, like you're implying, but it's dramatically lower.
I find it doubtful that the majority of these heists follow anything like the pattern you've described. I think much more likely is just something simple along the lines of "xyz was active in Bitcoin in 2011, they're still using exchanges as of 2020 because we have a leaked email database, they probably have either nothing or a metric ton of coins, let's give it a go".
If anything I think that someone shouting loudly "I have definitely sold it all, I promise" is a sign that they probably haven't.
Fiat money is harder to steal because you can't just transfer hundreds of thousands or millions about from mainstream banks without questions being asked.
For the most part I don't think that the GP has the story straight.
You can't really have it both ways - either Bitcoin is desirable to criminals because it's untraceable enough to get away with it etc, or it's not. I think that they're overstating the ease of finding a person's complete holdings.
Having said that, amusingly, if I had to think of the best way to force someone with a million dollars in a bank account to give me it... the first thing that comes to mind would be to hold them hostage and say to them, get KYC'd on a crypto exchange and send me the crypto. I think that the biggest barrier would be that with no prior history their bank and the exchange would throw a big fat WTF and probably lock everything down for weeks.
I'd say it's really a mix here: It's traceable enough to make Phil uncomfortable, but not every criminal will know it's traceable (especially by government agencies).
Your point is the big one though - one cannot suddenly, unexpectedly, and without a history of doing so, transfer six-figure sums without traditional financial institutions looking at said transaction fairly closely. Bitcoin doesn't have this drawback
There’s more friction involved in withdrawing money from a bank. You can do stuff like cancel transfers within a time window, something that’s not usually possible with cryptocurrency