First things first. This is topic is not to create a FUD rather a true talk to what is happening right now.
Can bitcoin get a hold to its investors to stay on him and keep believing on the power of the king?
For me, I can feel that investors are now turning their back against bitcoin because of this main reason. Tx Fees are very high and slow. It is not practical to be used on daily transactions which I think the first purpose why bitcoin was created.
You are correct about this, but let's not forget that bitcoin is still evolving. I remember when bitcoin passed $1000, and then it crashed and everyone though it would never get to $1k again. It stayed there during a lot of time but it fought it's way through it. It passed the bcash fork, it passed the china fud, it passed the segwit2x threat, and now faced a bit of Korea fud. We need the lightning network for sure, but I'm very confidant it will happen during this year (given a few recent news that some transactions were already made on the main network), and everyone that stays on bitcoin will be hugely rewarded by their patience with this coin.
For me, bitcoin can even go to $8k, I don't really care. It still has the biggest growing potencial of all coins, and the best dev team, so even if it fall behind other coins, it will then recover and stay miles away from them.