Let's say miners want to increase the 16 millions BTC limit. User don't want obviously. what happens?
Miners create software that allows larger block reward.
Miners run that software.
Users refuse to run that software.
Merchants refuse to run that software.
Exchanges refuse to run that software.
Miners create blocks and get a useless block reward that they can't spend and they can't exchange. Miners spend millions of dollars on equipment and electricity, and earn $0. Miners can't afford to pay their bills. Miners go out of business.
Meanwhile, users, and merchants and exchanges buy all the mining equipment that gets sold by the bankruptcy courts when the miners go out of business. Users and Merchants and Exchanges become miners, mining the original blockchain that does not have an increased limit.
Bitcoin continues, and stupid people (miners that tried to change the limit) lose money.