It doesn't make me sad or cause me depression. I could have bought more in the past, or spent less. But when I first learned about bitcoin I had already been investing for a while, and for many years I considered it too risky to put 100% of my investments there. The thing is that those investments over time have given me first financial peace of mind and then freedom of choice.
It is very easy to look at the past, see that profitability and think how wonderful everything would have been if you had bought a lot and not sold anything but the reality is that 99% who bought at that time sold after a short time, some at a loss. When bitcoin was something new, unregulated, that you did not know if it was going to be banned, with a much higher volatility than now, you had to be basically either crazy or a visionary to buy a good amount and hold on without selling for many years.
You're right, back then in my country, ponzi was on it's high and everything was treated in the same vein. Just like I mentioned, I was thinking Bitcoin was another Ponzi and never believed it has long-term potential. You cannot trust what you do not understand properly right?
Here we are today and Bitcoin has turned out to be not just a project, but a revolution. I'm still accumulating as much as I can, but I just wish I did what I'm doing now earlier.