So I'm left wondering... Bitcoin is a technology. The infrastructure is already in place for it to be used - smartphones. There are already existing paradigms that adults of all ages can use in order to make use of the system to make transfers.
Automobiles required roads, fuel and maintenance/repair support systems. The telephone needed vast stretches of cabling. The Internet required computers and communication hardware to be widely available. We are now in a period of Facebook, Instagram and WeChat where sudden and rapid user growth is a matter of software installation. The rails are already here, and general populations are starting to take interest.
Crypto (or at least PoW coins which are the only coins I would consider safe thus far) also have a problem of infrastructure...:nodes. You need a decentralized network of nodes. If your blocks are huge, then your transactions are validated by some corporation. If we all had affordable super computers ahead of the demand of transnational volume, we could run huge blocksizes at home and always be ahead of mainstream adoption's demand curve but that's not how it works unfortunately.
Same as mining infrastructure with it's centralizing problems.. etc.
So you either pay increasingly bigger fees for onchain transactions, or pay a tradeoff in a less-than-ideal transaction if you want to cater for the masses demands. Maybe this tradeoff cannot ever be avoided because it's some sort of physical limit? (like the speed of light or whatever). That is the trillion dollar question. If someone comes up with something that keeps your track record as safe as a strong PoW network without all the negatives then it would be a real bitcoin killer. What are the chances of this happening anytime soon? I would say rather low. Until then you have to live with what you have, and BTC is what we have. If this real bitcoin killer that defeats it on every department shows up, we would get rich as fuck since we would be the first to know about it (we would know at least in practice, since it doesn't work until it's in the wild, holding billions of a marketcap and not blowing up, but let's say it works in theory then on practice). Sounds too good to be true, so for the time being, you better hold some BTC, with it's cons and pros, it's what we have thus far. The other altcoin proponents have always some weaknesses that simply don't cut it and wouldn't justify mass exodus from BTC to them. Speculation is wild when some of these show up. Just see IOTA. You could have turned 1 BTC into 10 BTC the other day, during BTC's bull. It shows there's a demand for a "bitcoin killer", but like I said, in the long term it goes back to BTC since there isn't such thing yet.