Why would anyone pay in bitcoin if we think the value is going to go up?

I don’t think it’s too big an assumption to say that almost everyone who actually owns bitcoin thinks the value will continue to increase. So then why would anyone spend it on say a Tesla, Uber ride, etc?

To my mind, the best answers so far have been: to circumvent the government in terms of both prohibition and taxes, discounts, to take advantage of what you think is a high bitcoin value that will soon be corrected, and to take and spend profits.

Less helpful answers so far seemed to assume or centre around the idea of a 100% bitcoin economy or lifestyle. Obviously, we don’t live in that world now and the reason I don’t convert all of my fiat to bitcoin (since I think the value will increase) is 1) that’s a huge gamble and 2) the volatility.