In short, Bitconnect was a Ponzi scheme, a scam back in 2016. It lured people in by giving them initial profits, forcing them to recruit more people.
There’s an analysis on this article about how exactly their internal token was ripping off even the users that thought they were earning. https://medium.com/@anesthesteve/bitconnect-explained-c68dd2daef2f
In general, you should be very weary of similar scams on the cryptosphere, there are endless barrages of bots, comments promising profits, DMs on Discord and every channel that pretend to be someone famous and tell you to pump a specific shitcoin, stuff like that. Educate yourself and don’t fall prey to these scams.