Ethical nihilism is fine if that is your choice, but I think people usually make the comment you did, when they sometimes have principles, and other times compromise them if they are inconvenient.
Like, no one likes to pay taxes, but everyone loves a free government handout. We scream and cry if someone robs us, but if the government robs someone for us, we're happy to get a share of the loot.
The only way to change the system is to spend your life learning it and beating your head against its inertia. I choose to spend my time otherwise, and work within the system as well I can.
If you want a house, internet, a phone, a computer, health insurance, and the money to get those things, you have to live within some sort of modern society. If you disagree with modern society, you can go live in the bush somewhere and be your own man and self respect yourself right into life in the wilderness doing everything on your own, beholden to no man. Congratulations if you can do that. I'd rather not wipe my ass with leaves and watch my teeth fall out at 30 and dress my own deer and scratch at the lice and fleas that will eventually infest me.
Dealing with society means compromise.
I have principles when it comes to dealing with other people. I am empathetic to individuals.
Governments and corporations look at people as resources, not entities worthy of respect. Otherwise we wouldn't have indiscriminate wiretaps, no-bid contracts, monopolies, known unsafe products on the market, and a host of other afflictions.
I do not respect these large collectives (corporations, governments) because governments don't respect people; all they care about is profits, votes, reelections, market share, etc. I treat those collectives like forces of nature; they're there to be used or endured.