Trust can’t be earned, you give your trust or you don’t, it’s that simple. If somebody has to earn your trust, you will spend a lifetime making sure they are trustworthy. If you trust somebody and they abuse that trust, you will never fully trust that person again.
If you don’t trust yourself to do the right thing when nobody is watching, you can’t trust anybody because you don’t know what it means to trust anybody.
Of course, you can learn to trust yourself and when you do, you will be more lenient with other people. You will understand everybody can change, including you.
Remember: Everybody you meet in life is your mirror image, what you see in them exists in you.