I don't know about your ancestors, but we've lived the past millennia in societies where the regents rule over the masses in various forms. Mostly, those in power over those lacking that power, and who want to keep it that way. Money grants power. Therefore, the rich are powerful. More powerful than the poor. An example where you can see all of this in practice is Europe's colonial history. Furthermore, wealth is currently vastly unfair distributed. So what I quote from you, those tax laws you're likely referring to, don't make up for that. They don't fix that, not in the slightest; it isn't their goal either.
> Being outnumbered, they do not have the votes to defend themselves at the polls.
Outnumbered? Where exactly? On the contrary, right-wing Christians & liberals (European definition, not United States definition) together apparently defined as conservatives are steadily in control in the United States, United Kingdom, The Netherlands, and Germany. Occasionally a party like the Democrats (US), Labour (UK), PvdA (NL), or SPD (DE) get in control but they're quite on the right end of the left-wing spectrum. The only exception is the far right-wing nationalism which is on the rise. Examples are Trump (US), UKIP (UK), PVV (NL), AfD (DE). You can draw many examples for other countries & parties, such as France, Austria, Belgium, and many, many more.
If you speak about absolute numbers then see my comment about unfair distribution of wealth.
My explanation of corruption is far more simple: it is white collar crime. With crime in general, if people get away with being selfish (risk of getting caught), get no or low punishment when caught (lack of repercussions), and they're unhappy with their possessions & wage (equality, happiness) then it will occur more often. White collar crime, or corruption are no exception to this.