@listopencil is technically correct that vaping can't be stopped because simple setups can be created for vaping purposes.
@qorax did a vid about it awhile back, linked below (if you aren't subscribed to
@qorax youtube channel you should be!!).
BUT, there are many reasons that people choose to stock up. Perhaps you have tried a KF on a Provari and you know that it is a unique vape in and of itself and cannot be replicated. You decide this is a setup you can use for the duration of your life, so you decide you are going to stock up on the RTA and the mod that you love, so you load up on KF atties and parts and a good stock of Provaris. You are set and decide to now put your funds elsewhere (DIY, Nic, your other hobbies, etc.).
Another motivation or maybe together with the above you decide you aren't going to wait for the govt to restrict your favorite vaping devices, so you stock up on your favorites. Then there is no regulation that will be able to come between you and your favorite vape setup.
You know that push come to shove you could rig up some type of mech and a dripper but based on your motivations above you decide that is not for you (that choice is ALWAYS there), so you stockpile what you love and then cease purchasing. Or you only invest in some high end stuff that you want to try every now and then for hobby purposes.
Those are the reasons many of us choose to stock up on the rigs that we love (you will never simulate a Provari hit using a mech, and vise versa). So, why shouldn't I stock up on Provaris (or whatever)? If it fits my style and I love it there is no reason to wait (including the company may go out of business or stop manufacturing my beloved device

).