S-99, I used to have similar sort of trouble some 15 to 20 years ago in the primary school.
Everything started to click better when I just got rid of the surroundings and could do a fresh restart of my life, I think I have now had 3 restarts (for different reasons) and each time I feel becoming better and better. For now, you may actually laugh to whatever stupidity they tell you, but the reasons why you laugh or smile can be different - think Chinese. Sometimes the surroundings just *are* wrong and you are the only guy to acknowledge it, but rest assured you'll come across to an environment where that ain't so and when that happens it feels like a new chapter in your life. I suggest moving out. It is simply not worth it to waste your life in that kind of place, your work will never get acknowledged and your mind will become damaged over the time for that reason only.
I stopped advising people after learning the hard way that it is also the best way to earn their hatred, even if you were right from the get go. Far more better results are usually achieved by just ignoring the stupidity (or use it for your own advantage) unless somebody's life is in jeopardy, and only partake when they actually ask for your advice. It is a sort of perceptions game, whenever you say something like that, for some reason they misinterpret it to a different seriousness level than you originally meant it - or the message is somehow distorted to "I'm holier than thou" and that is against which they react. Even if it was only supposed to be a friendly advice, you end up burning bridges to that guy forever.
Calling people stupid is also a relatively easy way to burn bridges with them, but for some strange reason taking advantage of the situation they end up in is not (don't blame me, it just works that way) - I recall my brother selling chocolate bars in the army for personal gain of something like 200 - 300 %... man those soldiers become chocolate hungry after a week in the woods, and that's what he capitalized on it. Everybody knew they were being ripped off, but still they bought - and weren't even angry afterwards. Possibly because they still lost relatively small amount of money, but still.
Of course, you can also hint that they might want to reconsider something, but usually telling them that in a straightforward manner doesn't work, and they'll be angry to you because they knew you knew what was going to happen and you didn't prevent it from happening. Beats me how that logic works, but that's the way it usually goes. Sometimes letting people smack heads against the wall works best. We call it learning by the Siberian way, or Siberia teaches.
There are alternative ways of telling people they are stupid in a humoristic way, but that is a double-edged sword, you may piss them of even more if they consider it derogatory. My personal favorites are "Not all Indians are riding on that canoe" and "Not all bats are accounted for on that clock tower" or "That elevator is not going all the way up to the top" , possibly also "He's not driving with the high beams on". (I'd actually be delighted to hear more of these if you happen to have any!) But be sure to know what sort of person you are dealing with before doing this. Some people are capable of pulling this off in away that person does not get offended, while some people don't.
I'll now shut up about this topic.
