every year new singles, desparate and lonely will find their way to online dating. don't expect social sites to completely supplant them, not everyone wants to let their relatives know they a so lonely they'd do nuts in the ass on the first date
but like all things online, if you miss the initial huge adoption boon, or got in late, expect your earnings to be different, and scaled in a different manner than the whales you seek to emulate. slow and steady builds rebills too, something that won't ever change. patience and determination make for great profits, even with some dating sites at a high brand awareness level.