Scalability isn’t quite as simple as “how much data can a well-off enthusiast from a developed country store”. You need to consider the behavior of your lowest common denominator users.

You want as many users as possible to run fully-verifying nodes, rather than SPV (“simplified payment verification”) nodes that can be tricked by a malicious miner. The more transactions are being done through SPV nodes, the more potential payoff there is for an attacker, and the more resources they can dedicate to an attack.

Further, if your number of full nodes gets low enough, it becomes feasible for state actors to track down and compromise the remaining node operators. At that point, you may as well just be using a centralized, government approved payment system instead.