You're by no means the only one to realise this. You wouldn't know about how those animals and child labourers suffered if other people weren't reporting on it and campaigning against it. People actively try to reduce the suffering they are a part of inflicting by becoming vegan, boycotting products, raising awareness, protesting etc.
But, some people do well out of this system, so for them, it isn't hell- they are happily exploiting us! Other people- the majority probably, get a simple choice- comply to the system or become homeless. If they don't qualify for benefits- they will slip through the cracks.
If you want to understand them- simply look at yourself. You've just described that you will eat meat and know that the animal likely suffered while it was alive and when it was slaughtered. You know the products you buy are either made by child slave labour or contain components that are sourced that way. So- why do you/I do it? Because it's convenient. Because it makes our lives a little nicer. Because we've bought into the mindset that- everyone else is doing it, so why shouldn't we? We deserve that new phone or juicy steak. (Mine will be a pretend meat steak- I've made minimum effort to be vegetarian at least.)
You don't need those things to live anymore than a person would die on the spot if they resigned from their job. Most of us simply go with what we hope will be the least painful option in life though. For a lot, that may mean working a job they hate to bring in a wage they can survive on because homelessness sounds worse.
The majority of people have to work to get money to pay for those things and they've been convinced they really need them too- some things they do actually need- like food. So, in some ways, they may actually have starker choices than you do. Work to earn money or starve.
Plenty of people aren't all that happy about that though. Most people I know are tired, overworked and stressed. They'd all prefer a better work/ life balance. Maybe they don't see life as quite the extreme of hell. They may have enough good things or, see enough potential for good things to stop it being that.
Still- why do they comply? Because they would likely lose everything if they don't. They may not have any financial safety net at all. I think it's far easier to be a NEET if you have financial backing. Would you be willing to lose everything in order to join an uprising? Would you go without money = food, shelter, entertainment, recreational drugs? People would have to give things up if they quit being a part of the system. Most people simply don't want to make life worse for themselves because they likely recognise that that would be hell.
Sorry to sound harsh but- it's easier to gamble when you know you (probably) can't lose. If you know you're getting a paycheque (even if it's a piss poor amount,) no matter what you do, it's not quite the same as knowing your actions- or protest (not going to work) would mean: not only will you not get that paycheque, you'll likely be out of a job. You may have trouble getting references to find a new job. You may not qualify for benefits. There's a lot more risk for someone who has all that to lose, so that's probably why they comply. Plenty aren't happy about it though.