in 2019, there are 108.6 million card transactions per day.

so the block size increase should have done far sooner and radical if bitcoin is to be for mass adoption, 4MB per block under today's load is still treating bitcoin as if it is still a community currency. when we look at the mempool right now, there are more than 200k unconfirmed transactions, which you already can imagine how slow it is.

let's say a 2MiB block has 5k transactions on average, and the each block happens every 10 minutes, it means 720k transactions per day. if we have to match the 2019's rate, it is about 300MiB per block that equivalates 108m transactions per day.

but the problem is the entire blockchain which stands at about 526GB right now. we need to change the system of the blockchain synchronisation requirement to increase efficiency and decrease burden for those who do so. for example, fragmented blockchain which maintains blockchain size per user at a level they can afford to (about 15~100GB per user depending their ability and the network stability).

i still remember the earlier days using bitcoin wallet would take me at least a week just to do that at the time it was 75GB.