If you buy the 'iPhone Max' for $1500, you get ads, and if you buy the 'iPhone Max ad-free' for $3800, you don't get any ads in the app store, apple maps, apple news, or the various other apple services you use on only that one device. Similarly, you need to buy the ad-free edition of the iPad to not get ads there, and the ad-free version of the macbook for no ads there, and each of them can cost ~2.5x the cost.
I think that would be better than a monthly subscription since you'd just pay it once and then never think about it again.