I think it depends on the situation. If someone is planning to move abroad then they would benefit tremendously from developing their second language to expert level. Because it becomes essential to express your thoughts the right way. On the other hand, if someone travels to many different countries as a tourist then knowing a bit of every countries' language would make traveling more fun and bring more freedom without worrying too much about local people not understanding you completely.

I think it depends on the situation. If someone is planning to move abroad then they would benefit tremendously from developing their second language to a high level, because it becomes essential to express your thoughts the right way. On the other hand, if someone travels to many different countries as a tourist, then knowing a bit of every countries' language would make traveling more fun and bring more freedom without worrying too much about local people not understanding you completely.