Definitely. Most people who learn about Bitcoin seem to hear about it, and think "That'll never work."

I meanwhile had been trying to invent Bitcoin since I was a teenager. So my first response was "Dammit! I should have thought of that!". Pretty much immediately I thought it was a great idea that would work. It was only after thinking about it more that I realized it had serious technical problems, like the need for the blocksize limit, instant payments, etc. And of course, I devoted a lot of time to trying to help fix those issues. And we have done a great job fixing them, esp with the Lightning network. But there are still more issues out there, like replacing the miner subsidy. And of course wider political things like attempts to ban PoW.

So overall, my belief in the future success of Bitcoin has shifted up and down multiple times. And probably will continue to do so.