Guys can get horny much faster than they can get condoms.
If you sometimes think people are irresponsible for having unsafe sex, you are right. But it usually happens because an opportunity for sex arrived when they weren't prepared for it. And, of course, they didn't want to ruin the occasion by taking a break to go shopping at their local drug store.
Sex is spontaneous and nobody schedules their orgasms days in advance. So it makes no sense to hope for sex with an ideal guy, but to be completely unprepared for it when it happens. That's why all responsible gays guys make sure they always have condoms ready and waiting for when they might be needed.
If you don't own any condoms, maybe you're planning a life of celibacy, or maybe you just like taking enormous risks, or maybe you need to get some condoms now!