Can u gimme one reason why someone would be a racist or a bigot ?

I think the way they are raised.

Some people just have this inborn sense of different = bad. So I am straight and you are gay? That makes you different therefore bad. Exchange straight and gay for white/black or Christian/Atheist.

Its usually the less intelligent among us that are like this. Education and background can help you realize that different is just that, different. Not better or worse, just different. We thrive on differences.

I do love how bigoted people get so angry (and usually block me) when you point out they are being bigots. Makes me chuckle at their stupidity.

I think we often fear what we don't know. Rather than putting in the effort to learn about another culture, religion, political position.... whatever....we choose to oppose it based on our own ignorance.

Because that person thought he or she is better than other person from another race.

i think it makes them feel more worthwhile if they can think off someone else than being less than themselves,

Its divide and rule. Blame things on Muslims and black people (also of the 99%) and give the rich a free pass.

So they can shit on someone else.

Like you said in the post they get it from the environment or family they were raised in or from peers if not from the family.

It's a malfunction of the human species evolutionary biology in the modern world. We are kinda born that way but logic and reasoning over come it in most cases, but not all.