I don't have a strong opinion on mask wearing outside of medical and other vulnerable settings. What you've been doing before doesn't really change much the risk factors now, which will vary depending on where you are, what you're doing, other people's behaviour which may be impacted by mask wearing, and other factors.
Most people I know who work in hospitality and retail have been talking about how it's been barely a third maybe recently wearing one, you'll just be another one who isn't.
However I get what you’re saying but to call me selfish for wanting to do something I’m legally allowed to do is bit harsh.
Connecting legality with ethics or morality has many issues. Most of the time, legal is very minimum if that standard of behaviour expected and has very limited connection with social ethics and morality. Things can be legal and immoral - the law can even promote or require things that are terrible morally or ethically. Things can be legal and selfish, things and be legal and disgusting. They're really not related much and it's definitely not any sort of standard to hold ourselves to.
I've seen shops have to put up signs that they will not take bra, bikini/swimwear (including bottoms), or sock money because people will literally pull money out of their sweatiest places to hand over. It's gross, many would argue selfish and/or unethical, but it's still legal to do -- and legal for shops not to accept it.
I doubt most shops will enforce masks, just like most don't have rules on sock money, but they've every legal right to do so. That's entirely separate from the ethical or moral obligations, they can do it for the selfish reasoning of just not wanting to do so. It's not always wrong to be selfish, even if others have thoughts on it.