All of the above arguments could also be applied to dot-coms when they were in their early stages. I'm sure early adopters were as ecstatic as BTC early adopters. So it must not be a surprise when bubble crashes sooner or later, before cryptocurrencies become as usual as Internet.
But the dot-coms were companies not the technology. The success of the internet itself never faltered, it's just that people scrambled to speculate on companies to capitalise on it, and some terrible or highly risky companies got too much money. It's easier to say Bitcoin itself will succeed than it is to say that blockchain.info or coinbase will be the next google. There's also another dimension to crypto in that there can be an alt-coin bubble in parallel.
So, with the dot-com bubble, pets.com is often used an example of the crash. The pets.com of crypto could be a company (e.g. gox), or it could be an alt coin (e.g. litecoin), but it's not crypto itself. Just as HTTP and SMTP (email) went from strength to strength, so will crypto.
On the otherhand there is a possibility that another crypto overtakes Bitcoin, but this won't happen overnight, and any Bitcoin holders would have plenty of time to diversify towards the alternative before suffering any real loss.