the point is to make such a cryptocurrency (let's go wild here in si-fi universe) that people would want and can afford. something that will be:
* easy/convenient to use, cheap (low/no fees) and fast (processing time);
* transparent, secure, decentralized;
* capable of self-defence (possess a mechanism against manipulation and abuse of the system) and governed by the users/holders (different level of voting and various electoral, autonomous bodies within the system that counterbalance and equilibrate each other to avoid corruption and abuse of power);
* suppressing/making unnecessary an urge for greed and unreasonable enrichment (fee if you hold more than you need and speculate);
* stimulating trust, help and support for those who are in temporal difficulties (unforeseen circumstances, illness, etc) but not the LAZY one;
* discouraging laziness and make no room for freeloaders;
* ...
You need a smartphone or laptop, you need internet. Poor people may not have that. So it's not as convenient to use as you want to present it.
A crypto that has low/no fee and fast processing will not have miners, because nobody will work for free, nobody would pay for electricity for you and so on. What you ask for is a centralized garbage you'll call cryptocurrency. So it's a no.
As just said, that will be either insecure (no miners) either centralized.
If you want self-defence at these requirements, only the centralized option remains. Until now you have proven that you don't understand crypto. Now you continue by proving you also don't understand economics. You want things you cannot do. There's no way to preserve value for this... proposal on the free market.
Then you want to do something with money.. something that cannot be done with money. It's human nature. How on earth can "discouraging laziness" for everybody if they get for free what they need?! What planet are you from?!
will unlimited supply be a cause of inflation/decrease in value and other issues of current monetary systems?
will reversible transactions complicate the system, make it less secure and stable?
Yes, but else you'll end up without coins because that you'll continuously waste them. But since it'll be a centralized system, maybe you'll handle with reversing transactions for unused money after a while and you won't need unlimited supply after all if you don't want to.
On a proper blockchain reversible transactions are the worse possible idea. But here reversible transactions will be just fine, since the system is centralized and only yours. And it will not be a blockchain either.
You never answered how people will get this "coin" without it being for free, but still not having to buy it or work for it, hence everybody, including me, still assumes you give it for free.
Also, I think that you fail to understand that you are heading towards a wrong direction, one that cannot be implemented and sustained.