I believe that holding your own keys is not that expensive. Forgetting an offline hardware signing device, you could just use an app on your phone, if you don’t have a phone roll some dice to generate your seed words that you store on paper. BUT, if you’re talking about affording the fees to transact on layer-1, then there may be people that can’t afford the fees (especially with Ordinal inscription speculation filling up the mempool). These people may be more in favor of asking their “bank” to hold their bitcoin, which provides them a layer 2 channel for cheaper transactions. The upside is that Banks won’t be able to fractional reserve re-hypothecate as they do now.