If this was really true, than why do low-income people (who pay a higher tax rate than the rich) vote at lower rates (because of voter suppression, employers not giving them time off on voting day, lack of transportation, etc.) than billionaires.

A better way to think of this is: Teenagers are affected by almost all laws, and are expected to follow them, but have practically zero say in voting for them, while someone who is elderly, sick, and 6 months away from dying (who will not be around to see the laws take effect, and who will not be affected by them) can vote…

Sources:

https://www.cnbc.com/2021/09/23/americas-richest-400-families-pay-a-lower-tax-rate-than-average-taxpayer.html

https://www.nytimes.com/2020/08/11/us/politics/poorer-americans-have-much-lower-voting-rates-in-national-elections-than-the-nonpoor-a-study-finds.html#:~:text=The%20study%2C%20by%20a%20Columbia,above%20twice%20the%20poverty%20line.