young people have no memory of the past

governments must mandate compulsory defined sex education for every child - no exceptions or opt-outs (parents do not own their children) - and continue to fund ongoing public awareness

I know a few guys in their 20s who are HIV+

One went out looking to get infected. He wanted to be like the guys he looked up to. Not sure how popular Poz parties are these days, but years ago they were the rage for a while. However I do know there's a fairly cavalier attitude towards infection out there. Seroconversion no longer equals death and that may have a lot to do with how people view condoms and safer sex.

Women use birth control to prevent pregnancies, gay men should approach PREP in much the same way.

People in their 20's are adults and as such responsible for their next own sexual health. Sex Ed including comprehensive HIV info will help but is not the definitive answer.

As Ashi said, PLAY SAFE. It is your responsibility to stay healthy. You cannot rely on others.

Carlos is right. If you're insurance covers it, there is no reason not to be on PrEP if you sleep with multiple people. 

PrEP isn't a panacea. All drugs have side effects which may not become known for some time. One known side effect of PrEP is possible kidney damage. Also it should be used in combination with condoms.

And for minors, who aren't going to get access to HIV prevention drugs anyway, sex ed is the only viable strategy.

Yes, some people are irresponsible on a frequent basis and are cavalier with their sexual practices, but let's remember, too, that infection can be just one mistake away. Perhaps you drank too much, partied a little too much recreationally or maybe somebody worked very hard to get you that way.  Forced rape is also a possible cause. Then there is the path of intravenous drug users sharing needles. The truth of the matter is that we shouldn't play guessing games and people in the field of medicine should definitely not being playing this game.

No one preventative is enough. Gay or straight, we ALL need to be careful and aware. Measels is a rare occurrence now due to vaccinations. But would you let your little one go play with a child with measels because he or she has been vaccinated?

PrEP helps, but is no excuse not to be careful.

Anyways, many medical insurance may cover HIV screening without pre-authorization (doesn't need your primary doctor's referral), do a check if your insurance covers it.  I know at least Medi-Cal (California's Medicaid) covers it.