Paraphrasing @vitalik.eth just now at TOKEN2049 Singapore:

Transaction fees have historically been the roadblock to actual crypto adoption, ahead of UX. The cost of transactions killed off the early and earnest efforts to use either BTC or ETH for day-to-day payments. In places like Argentina, people use crypto but have moved to doing Binance-to-Binance transfers, which are free but also centralized and custodial, which defeats the purpose. However, L2s now offer sub-cent transactions, opening up a new era for payments.

Wallet UX is also getting better (e.g., Daimo) but TradFi payment rails have kept up with usability improvements of their own (Venmo, SEPA, etc.). Crypto can bypass the int’l politics that are the main limiting factor in cross-border TradFi payments.

Crypto is ultimately digital concrete — blockchains are robust, permanent structures. With digital concrete, we can build digital castles in the sky.

[Personal note: I love the fresh idea of ETH as digital concrete rather than digital oil]