> Did you like this post, please buy me a coffee?
are completely okay! I don't interpret it as 'begging me for my money'. They are not nagging, and you do not have to buy them a coffee/pizza/metaphorical food item. You can go on with your day. But maybe someone thinks that the post deserves a token of appreciation, and tossing someone one, maybe two euros doesn't hurt. Just like tipping. Good = no tip, exceptional = tip.
> I know how much 4€ is, that's about two icecreams, or three beers. Off topic, but is OP finding these? Are certain countries in Europe really this cheap??