All the BTC investors just had a difficult year in 2018.
A lot of people had chosen to give up, while more people continued believing in BTC.
As for the price,what matters will influence the price in 2019?
BTC Forks? Lightning network? Miners? Whales? Investors?
For the people who are holding since 2015 and from the bitcoin prices lesser than $300, last year was not a difficult one in some sense. I agree that could be more disappointments in 2018 as most of the speculations were referring something completely different. But, it is the a and we cannot expect always only one thing to happen.
Out of the factors given by you which will be influencing the bitcoin markets in coming months, I am believing in to "new investors". Yes, how much of bitcoin market is going to convince the new investors and institutional funds will be the key for what is going to happen in 2019. Institutional investors will get easily convinced when they are watching market is about to start.
But, the real kick starter will be new investors as they only will trigger the institutional investors. But convincing new investors to get into bitcoin adoption is a very big challenge. Agree or not, they are the real deciding factor on how this year will be.