It really does take a lot of time and effort. Even those who start young, find they have to take refresher courses and practise abroad or their hard-won skills slip away.
There’s always someone out there making the effort on your behalf, who will understand English when they pick you up on holiday in their taxi or sign for your football club. Let them put in the effort.
We’ll probably all speak the same language one day. Or, at least, have a chip implanted in our brains enabling live translating.
A little time spent on Google searching for real reasons not to learn a second (or third) language is quite a fruitless task. Remove the word “not” and you’ll have a busy few weeks reading lists, academic peer reviewed papers and anecdotal blogs… it’s all there.