I m always told that I m such a nice guy, should I change that?

If you want certain things out of life that you don't have right now, then you have to DO what it takes to get them. So just BEING a different person may have little to no effect on your circumstances. There's not some magic force in the universe that you can appease by being the right kind of person, some kind of code you can crack, to make all good things just gravitate towards you. Each thing you want may require different actions or a different skillset in order to get it. Being more assertive can make you better with women. Assertiveness isn't magic that just makes any girl you want fall into your arms. It just increases your chances. As far as I can tell, we don't live in a world of absolutes. We live in a world of probabilities. No such thing as a guaranteed outcome. The best we can do is increase the likelihood of a desired outcome.

The idea that a$sh0|es just get whatever they want effortlessly is also an illusion. A nice illusion. But an illusion nonetheless.

The worst thing a woman can call you is a nice guy. It means you are a wuss.

If you want to get women and gain respect, all you have to do is act like a gentleman who uses the word "No" to women. They may get a little pouty or even angry. You smile and reply with "What's wrong? Hasn't a guy ever told you 'No' before?" Saying 'No' to a woman gets respect, even if they cop an attitude. It pays off in the long run.

Asshole men get asshole women only. Don't first that. Those type of women are only attracted to them for either their wealth or body.

You have a nice personality, you'll find yourself a women who would like your personality rather than anything else. Wait for her to come in life. One day will come!