Don’t worry, did you try to use bitcoin so far? I did a few transactions to send e.g. 0.001 BTC (around 8 USD now). In order to receive them fast I need to pay high fees, like the equivalent of 3 USD. Or I can use low fees and wait days. Does this look “mass adoption” to you? Not to me…
That’s why there is Lightning. In the future, instead of using many expensive on chain transactions, the mass adoption will happen on Lightning, where you can even send a few satoshi almost for free.
I did a little calculation, it’s approximate, but just to give you an idea.
1 block is approximately 1 MB
1 block is mined every 10 minutes
So if you like Spreadhseets you can easily do the math yourself, here a screenshot:
The calculation is wrong, because a block is not exactly 1 MB.
We know that bitcoin is already 10 years old and the blockchain is around 250 - 300 GB in size, so to reach 400 GB it takes much longer than in my pessimistic calculation, which shows we should have already reached that number after 7 years.
Anyway, with the same pessimistic calculation, we’ll reach 1 TB size after almost 19 years. We already can easily afford now 1 TB disks and buy cheap VTS server offering 200-300 GB space for 5 USD/month.
In 10 years I’m pretty sure that memory will be much bigger and cheaper than now.
Also, we won’t need to run a full node. There is Neutrino (light client which won’t need to have the full blockchain) on the way (it’s beta but it works well enough at least in testnet), the bitcoin client created by lightning labs.
Even the official bitcoin client allows to run bitcoind in pruned mode, which means you can set it up to keep the amount in gigabytes you want. E.g. just the latest 30 GB, or set it to keep the blocks from a specific date (it’s important for lightning to keep the history at least from the moment a channel was created).