Why is online dating filled with low quality men?

I've been online dating for a long time, many years already. I can say that 90% of the guys online tend to be very low quality men. Perverts, men with mental issues / problems, attention seekers, cheaters, guys who can't hold a conversation. Meanwhile all the good guys that I am seeing tend to be men that I meet at my job. Non creepy, all around good sane guy. why is it that low quality men that tend to flock towards online dating? why aren't there more good guys that are marriage material on the internet? they're all at work! LITERALLY!!
Why is online dating filled with low quality men?
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