From where do you build your self-esteem?

By being:

than other people?

This is comparative self esteem, and relies on what sort of person you seem to be compared with other people. Sometimes it is done like a game which isn't much fun: this game is known as one-upping. For example if people were considered important by the length of their toes, then someone you know might claim their toes are as long as mice. Wanting to seem more important someone else might claim their toes are as long as cats, and someone else claim their toes are as long as puppies. Without taking off their shoes, it would be hard to know who was correct. Meanwhile they are unhappy with one another for each claiming to be more important than the other by one step.

Yup, toes as big as me!

If someone tries to play this game with you, you can do several things:

"More" or "less" comparisons do not need to be made with other people. A sense of success is an important part of building self esteem. Success can be measured by how well you are doing now compared to the past. You can also believe you are smart, fit, and creative, take pride in that, and allow and agree that other people are also smart, fit, and/or creative. Two or more people can be smart without that lessening anyone in that group.

I'm just slime.

Another comparative situation is when someone decides that they are worse off than everyone else. This is a negative form of success, but one easily achievable. Usually, people who choose to make or see their lives as worse than anyone else's do so because they are hoping someone will offer to rescue them. However, they may not allow anyone to help them. They can be afraid that they may not be a success at anything else, even though this sort of success is hurting them. You can ask for help at any time you need it. You are always a success when you choose to enjoy your life.