As far as simple quotes go. This sounds optimistic, yet reasonable.
Based on your advice, maybe I should just go to Thailand and freelance as an app/web dev for 3 days per week and play guitar / make electronic music for the rest. I'd wonder how I'd prepare for economic down turns though.
I'd make about: 5000 euro's per month (@ 50 euro's per hour as a freelancer). Living on about 10000 euro's per year, I'd save 20000 euro's after taxes (Dutch, high taxes, yay!). Regardless of that, I guess I wouldn't need to worry about recessions after 2 years of part-time remote freelance work, not in South East Asia anyway.
Sounds doable, at first glance. I need more glances. Especially the, "what about my girlfriend, friends and family?" glance.