and why do you think that?
2017 was one of the best years for bitcoin both in moving forward with the technology and the mass adoption of it as a currency. so i don't get why you say it was not related to actual growth of it!!!
for starters in 2017 we saw the end to a 3 year old debate for scaling bitcoin and we finally moved ahead with development. it opened up way for at least 4-5 other things such as LN, Schnorr, Signature aggregation.
on top of that we had multiple big adoption cases such as Japan where their government accepted bitcoin as a legal way of payment. so the big ATH wasn't really that surprising considering all these actual growths!
Hence, we can't say the improvements helped bitcoin reach 20 thousand dollars, we can say 20 thousand dollars helped improvements get done quicker. That is what I think the original poster you answer to means, of course I don't know him so I can't say for sure but that makes the most sense. Whatever improved in bitcoin, either the technology, or the interest, or even the financial funding provided to crypto companies all happened on the worse bear market of our era.