Sheesh - you're better off than a lot of US-based developers I know. Not everyone lives in SF or NY, and not every developer pulls in $100k+ (many do, but not all). I know plenty of jr-mid level devs not pulling in $100k. $7k/month is more than some of them make - certainly couldn't save that much.
Were you contracting for US companies in your previous remote job?
My expertise is Scala, "Big Data", some machine learning and AI, plus generic Java/Spring/etc experience. My last job used only Scala+Play from that list. They were willing to hire remote people from across the world because (I assume) it would cost even more to hire experienced Scala devs in SF.
BTW if you care about saving money then London's contracting market is IMO even better than working remotely for US firms. It's worse now with the pound going to the toilet after brexit referendum, and will probably soon be only a memory for us foreigners though.
I'm saving that much on an ongoing basis at my full-time job in SF.
I do have a roommate, but, to be honest, the weather alone makes it worth it.
I feel like I'm rather average developer, and live in Poland (more expensive than the countries you listed), and still managed to save over $7000 per month in my last remote gig. No roommates either (I live in a flat I own). I feel that I'd be MUCH worse off in SV, or in the US in general.