I agree that the price is still high, even $5000 would be a good price.
But how to know why these people that have caused the rally invested?
Since about $3000, price upswings have been related to hopes to get "free coins". It may be a simple correlation and not a causality, but I think a big group has invested in Bitcoin in those last 3-4 months with Bitcoin Cash, Bitcoin Gold and Segwit2x "free coins" in mind.
It could be related to that but the main trend is telling us something else. Whatever it is, I do not know. Maybe it is because of Bitcoin's nature as deflationary currency combined with the increased demand for it.
Maybe there are bigger forces at work here that has not yet revealed itself. Drugs, money laundering and other illegal activities are still a big part of Bitcoin whether we like it or not.
Then that is good news for you. You will have plenty of time to buy more cheap coins.