swim against the tide
US /swɪm əˈɡɛnst ðə taɪd/
UK /swɪm əˈɡɛnst ðə taɪd/

1.
to go against the general opinion or trend; to do something that is not popular or goes against what most people are doing
:
•
He decided to swim against the tide and pursue a career in art, despite his family's expectations for him to become a doctor.
•
It's hard to swim against the tide when everyone else is doing the opposite.