I don't mean to be cruel, but I think you know the answer. You are just wanting someone to feed your dream and then before you know it you will be another 10 years older and nothing to show for it.

So, why do you feel like if you take a job to improve your life you will never be able to aspire to a better living? If you truly have the talent you say, I'm not doubting you, why would an entry-level job, in your chosen field, not lead to better and better paying jobs? Perhaps you won't be self-employed, but you still can achieve success. Success might not look like you envisioned but it can still be rewarding. You have been chasing this for 20 plus years, don't waste another 20 years going down the same road. 

Stop tell yourself things that aren't true. Nowhere, I mean nowhere did any building cost go up by a factor of 5 or 10! That is insane claim that nobody here is going to buy.  

You need to wake up. You state you have no relationship with your sons. Nothing is more important than family.