i missed my domain name

Guys, i was having a good domain.
bought it for one year, then in last months, i stopped working on that site, forgot about that. Domain got expired. i got late to renew it. then i tried. but it was kept by some company. Now they want 6000 USD for that. lol.
I dont get this logic. do comanies buy those all expired domains and sell?
whats the cycle?
please xplain anybody

That happens. Yes, most of the reasonable names is in hands of domain traders. Pretty sad. You may tell them your price and just move. There is still a chance they will sell it to you for your price but make sure they are not scammers.