You give the anwer to your question. "Heck, I don’t even have a salary anymore but yet I love to work." 

You like what you do. You're not insane, you're only part of the 0.005% of people in this world that like what they do to the point of doing it without earning money.

You need a money base though, and that's where the problem is. If everybody would have food, shelter and minimum heath care assured there would not be 0.005% like yourself but 75%.

But that's not the world we have yet, because probably people with power don't want to give up the power of controlling the masses with the most poweeful tool they have: fear! It's really sad but that will change. Maybe one more century needs to pass though.

Well, who wants to seat by the beach all year? Kinda boring no? 

We do not get paid for our hobbies, but often work very hard at them.  So the answer is simple - because you enjoy what you are doing.

You are lucky that your hobby pays!

I think Daniel Pink's book (Drive) may have something to say here. I haven't read it myself (it's been on my list for a while), but I've heard the high level summary from a lot of different places: money isn't actually all that good a motivator for intellectual work, once you've hit a certain point where it's no longer something that needs to be worried about.

After that point, according to Pink, your primary motivators are autonomy, mastery, and purpose. That is, you get to decide what to do and how to do it, it's something that challenges you and forces you to improve, and you can see a greater purpose for what you're doing.

My guess is, you're well past the point where financial incentives have any real pull on you, and you're instead working on things that interest and challenge you, instead of just the ones that pay the bills. I wouldn't be surprised if you're enjoying your work MORE than when you were making money doing it, just because you're working out of interest instead of necessity.