73% of the population is identified as 'white'. That means a much larger pool than any other group from which to pull candidates, and therefore a higher chance of having a candidate with whatever makes a 'winner' in politics.

50% are men, so all other things being equal, you'd expect half the candidates to be men... but all other things are not equal. Women make up ~25% of candidates these days, so the same fact applies as with race.

You're simply more likely to get a 'winner' that is a male because of statistics.

Once you accept those two things, you can go on to talk about other things that could be tilting the playing field. Those who have been in the majority historically have a higher likelihood of belonging to a support structure (a social network) that increases their odds of winning. Those who have been in the majority historically are also more likely to have greater wealth and education.

In short, there would actually be something obviously wrong if the fielded candidates suddenly matched the racial and sex demographics of the public this year. It would be an indication that people are being elevated because of their ethnicity or sex.

There's nothing wrong with looking for irrelevant barriers to remove, but there is something wrong with such a shallow analysis of the field as 'too many white men'.