What should i do ?

I'm experienced in backend development. When it comes to front end, I just suck at it naturally. I'm not sure why. Maybe I don't have the brain to "design" ?
Should I hire someone to develop my front end or should I learn front end ?

I'm not into programming, so I do not know how hard is to learn fronted programming, but I would go the following way.

If your time to learn front end and outcome from that is lower than focusing on back end and paying someone to do front end, then you should hire someone to do that. If you believe you can earn more in long term by learning front end, then go for learning it.

I would suggest for you to , team up with someone who might have same interest , need for business and try to make monies with backend + frontend web agency or whatever way you are looking to monetize this.

Ofc who is good in frontend

Bootstrap and bootstrap themes exist for people like you.

I know what you are saying dude, I'm a backend dev to.

But today front end can be pretty easy. Learn a front end lib/framework such as vue, react or angular.
Get some ready to use templates and you are ready to rock on your front end web app