What I don’t think they realise is the existence of this limit will cause some unusual psychological behaviour and people that never would have hit it will find it uncomfortable enough to stop using it entirely.

This also why in the early days of ADSL and eventually fibre uncapped home Internet, the ISP would have something called a Fair Usage Policy (FUP) that they’d keep hidden from most users, buried in portals or fine print. The FUP was essentially a soft cap that would excessively throttle your internet speed if you hit the cap. Most users would never hit the cap, so keeping it “secret” was seen as the best way to deal with it, to prevent odd behaviour by users such as switching off the router at night or limiting internet hours.

What’s old is new again.