I learned 2 years of French in high school topped up with some Youtube and Duo Lingo.
If you have no passion for it and have to ask "what is the point" then you shouldn't be doing it. It's better to spend your time on something you're passionate about and where you can learn something new, ideally a skillset that can generate money.
Unless you go live in France or whatever for several years you're never going to come anywhere close to a native speaker so there's little point in investing your time into it unless there is some kind of reward you get out of it (hot french gf? can you get a job where it is useful? are you just passionate and interested in learning it and it brings you happiness?)
On top of that AI translation tools are pretty fucking kosher right now and are only going to get better - but if you want to have real conversations with people in their real language then go for that option.
Languages can be good for life experience and general knowledge in some cases but in others I think some people end up sacrificing their ability with the English language. You're British so you're obviously already at a disadvantage (because British people can't speak English) so if you're not passionate about other languages I would suggest to focus your time on the most widely accepted and valuable one (which is English). Become like really, really good at the English language through reading and talking and become very, very good at it instead of just being very good at English and average at some other languages you don't have any passion for.
Like all this duolingo/YouTube shit you do, you're not really going to make leaps and bounds unless you fully go into it - I guess if it interests you, you could just keep doing stuff like that as a hobby but if you're seriously questioning why you should even do it, then don't do it.
Whether you have passion or not for those other languages or you see value in them (like are you planning on ever living in France?) is totally up to you. And besides learning English and perfecting it (it is basically the main language of commerce) it is a very good idea to learn how to
communicate very well. Like your OP was a bit too long for my taste, you could've shortened it a bunch.
Also: my own personal experience is that it can be more interesting to go to other places and not have a clue what their language is. You can have more interesting conversations and meet more interesting people that way and it can also have the opposite effect.
