Well, some people say that the 2017's sharp rising resulted from the previous halving in July 2016. It just took some time before the 2016's halving had its effect.
It is not just an assumption but a fact, the halving was in 2016 and we had the best rally in the market by 2017 and this time also i am expecting 2021 to be the best year for the bitcoin market if everything follows the same pattern.
So, we can't say that we had the same supply when BTC was $550 in August 2016, and when it went up to $20k more than a year later. In fact, we can say, even without looking that up, that the supply was shorter or the demand was greater, but the situation was definitely not the same.
The difference was that there were many new investors in the market and the hype surround the bitcoin market was really huge and the introduction of options market all helped the market in a great way.