So I just started using the app called Rmabox and it seems pretty useful. Actually I am ranting using the same app. Keeps all my social profiles at one place. But I am concerned about my privacy as well. Is it safe to use such apps which help you to manage all your social accounts at one place? Will that not create a single point of security breach?

Let's go read their privacy policy.

1) no link
2) no link on terms of service
3) EULa - no link

Rotates phone
Oh we have links now 🤦‍♂️

Well... let's just say, you handed over your login credentials to a company that now stores these.

Up to you how you feel about that problem.

I quote:
Our Apps offer you the ability to register and login using your third party social media account details (like your Facebook or Twitter logins).