That's because of the "language tiers".

People don't usually learn languages for fun, at least not to a point where they can actually speak it fluently. They learn it because they have an use for it. If you learn a language without having an use for it, you lose it quite quickly.

The highest tier language is the worldwide lingua franca: English. You learn English to talk to anyone, not to talk to English native speakers. For example, my company (a central European one) uses English as the work language. We don't have a single English native speaker on the team. But if I want to talk to a colleague from Rumania, Egypt, Spain or the Netherlands I will talk English with them.

The next tier is the regional lingua franca. That's e.g. Spanish, French, German, Mandarin, Russian or Arabic (and likely a few others, I don't know the whole world). These languages are spoken in certain regions and can be used to communicate with people from neighbouring countries. You can get around with e.g. German in Hungary, because most Hungarians learn German. It's also sometimes necessary since TV, books or other media might not be available in the local language. For example, a lot of Albanians speak Italian, because TV shows and movies are rarely translated into Albanian and instead broadcast in Italian. (Also, since Italy was so close, many people watched Italian TV while Albania had communism.)

The lowest tier are local languages. These are languages that are only spoken in their own country. For example: Rumanian, Serbian, Hungarian, Welsh, Gaelic, Dutch and so on. People speak these languages because they live in that country. For someone who doesn't live in that country, there's rarely any major benefit to learning these languages.

In general, people only really learn to speak languages that are on the same tier or higher.

If you live in Albania, you learn Albanian as a child, then probably add Italian to understand TV. In school you will learn English and once you go online you will use it. You might also learn Russian to be able to communicate with people in nearby countries and if you are from the muslim part of Albania you might also learn Arabic.

If you live in Germany, you'd just learn German and English. No need for any other languages. If you spend some significant time in France, Spain or Italy, you might pick up one of these languages.

If you live in the US or GB, you start with English, and there's hardly any point to learn anything else. By default you can already communicate with everyone, read everything on the internet and watch all TV shows and movies (pretty much everything is translated into English, if it isn't even refilmed in English). If you try to learn another language and try to use it with native speakers of said language, chances are pretty high they just switch over to English.