I had some success, then got obsessed with AI. After 1-2 years studying nonstop figuring out what to build I ran out of money and had to consult.
I would have made more money working full time... but perhaps not if my next project goes well.
That said, even with what I know now, I'm about to do it all again. The freedom is priceless.
Risk is scary. But going 9-5 to a job hoping for raises, good bosses, and stock liquidation events is even scarier IMO.
It took me a while to figure out my optimal "toolkit". Productivity-wise, my essentials are a Roost dock, Logitech wireless keyboard, and Logitech wireless gaming mouse. Working from cafés is really great now. (And my shoulder pain is gone!)
Productive travel advice: don't do hostels. Airbnbs are awesome, but only pick ones with private rooms that have a nice desk and chair. It's way more convenient than spending extra money on a coworking space (unless that's your thing). If you're planning to actually get work done, stay in a given city for at least two weeks, and preferably more than a month. Traveling to a new city always takes some adjustment.
I started with $100,000, but that's way more than you need. (I just didn't have very many expenses over the course of my SV career.) When I was Airbnb-traveling in Europe, I think I spent about $30,000-$35,000 a year when all was said and done. This was very comfortable living in Western Europe though, and I probably spent about half to two-thirds of my time eating out. You can definitely do $20,000 or less a year, especially if you visit cheaper countries, sublet places for at least a month, and cook for yourself more.
If you have more than, say, $10k in savings, put some of it in FDIC-insured accounts with ~1% returns (e.g. Ally), and invest some of it index funds (Vanguard). It's basically free money unless you happen to invest right before a major recession.