We can all wax lyrical and paint pretty pictures about the noble goals of DEI. But till we get an equal and fair world, the ugly picture is that DEI starts by dividing the pie into smaller parts, and taking from one to give to another, instead of making the pie bigger for everyone.
And if history is anything to go by, most "DEI"-like efforts never ever reach that end-goal. They perpetuate indefinitely until they create yet another oppressed or previously-disadvantaged class, and the cycle will just repeat.
Yes that makes it more competitive.
Or less-competitive at an advantage to some and both others if it stayed the same way.
This is the first time I've heard that. The normal party line is that, yes, they're worse at the job but it's because they never got the opportunity to learn. You can observe in colleges that DEI-appointed students do massively worse overall despite probably being given even more leeway than normal students.
Ask yourselves, who paid for your education? Was it pulled up by the bootstraps rags-to-riches, or did you get help from e.g. family? Where did you grow up, and how did that contribute to your current career / life?
Now imagine you didn't have those opportunities, because your family (going back generations) never was able to build up generational wealth and comfort.
DEI is an attempt to make up for that. Is it ideal? No. Does it come across as discrimination to the priviledged people / classes? Sure. Does it personally affect you? Probably not, but I don't know you (generalised you, the reader).
That said, if you don't like DEI, vote and act accordingly. Work to make sure everyone earns a liveable wage, owns a house, gets a good education and consequent steady job opportunities regardless of familial wealth. Be and act anti-racist and anti-classist, because it's not enough to simply "not be racist".