How much did Bitcoin really change between the 2013 and 2017 bubbles?
With that in mind, consider that the market rose from the $200s to $20K. When we were in the $200s, someone with your mentality would never have believed price could stay above $3K (or $10K, etc.) for such a long time. And yet we have.
Speculators are buying up all the BTC. They have been since inception, really. That throws a wrench into this theory that everything is dependent on big improvements in utility.
In fact, I separate the speculation component and the real use of bitcoin, I understand that they are related, but I am more interested in the real use.
You ask about differences by implying that they are either absent or insignificant. But tell me, could we imagine in 2013 that bitcoin would have a bandwidth problem? How often did we see this problem in those years?
It was being discussed as a practical issue by early 2013, and a theoretical issue long before that:
https://bitcointalk.org/index.php?topic=1347.20In fact, in 2013 the 250kb soft block size limit was lifted for this reason. In other words, in 2013 it was well known that Bitcoin had very limited transaction per second capabilities, and may continue to have those limits going forward.
And in 2017, this problem has already become a new reality. We can call it differently, but the fact is that bitcoin/its demand has radically changed.
Adoption and accumulation continue, sure, but the fact that BTC exponentially increased in price in 2017 goes to show how disconnected price and underlying utility can be. Speculators just don't care about fees and congestion.
And now if you look into the future and think that "speculators and their influence on bitcoin will be the same as in the past, technical improvements are not critical", then I think this will be a mistake.
That statement would be a lot more valid if BTC were trading in the $3,000s, or below $1,000. As it stands, it's obvious that demand is extremely strong in spite of the same limitations that existed after the activation of Segwit in 2017.