my biggest investment regret that I put my investment money on forex despite I could buy some btc. I couldn't make money with forex but btc did rise incredibly.

Majority of the people who owns a coin right now experienced the same thing. I myself had the same experience.
Only few people believed that bitcoin will be on the situation where it is right now, but that is a good thing. Investing
on the coin right now is not too late we can say that right now it is on it's toddler stage and has a lot of stage to come.

i know bitcoin earlier and the regret is not investing on that time i waste my time to do faucet and i didn't know that you can buy bitcoin in remitance center... if i do that early and that time is i know how to trade? maybe i have  enough of coin right now maybe i can buy what i need for now....

While I regret too, I don't think it's worth worrying about. I suspect that whenever you buy you regret you didn't buy it sooner, even those people who bought it when it was less than $100.

I feel the same regret I first heard of the coin when it was $900 a piece but never invested on it.
Thought it was just something that will eventually loss its value.

I decided to invest on it when the price was already at $3000 a piece if I made it before I should have bought 3 coins rather than having just 1.

My investment regrets in bitcoin is I dont buy when the price of bitcoin is very low.....and now the bitcoin is almost $6000...But they say its better to be late than never..so right now im focus in building of mining rig...and in joining in some campaign..

i think many of us have the same regret to not buying the coin when the price is still cheap and now the price is jump into hundreds dollar and its normal to  feel like that. but if we can learn from our mistake in the past, i think we can make decision to buy the coins when we think that the price can increase soon so we don't have to regret again. and i think this is the reason that we should learn about analyze the coins that we want to buy so we can determine the right price we want to buy.

Wish I had bought more Bitcoin before hard forks
Should have went harder in some icos and less in others
need to reinvest
learn to take emotion out of the equation

Well i will share my investment regret whereby i took debt to invest in bitcoin scheme and it turned out to be ponzi one and i still had to pay
the debt. 
I suggest you to pay what ever debt you have before you put your money into bitcoin, you can have it all, the profits you can gain and no more problems if you pay first right? And who knows bitcoin will grow more so you can get large profit with out thinking those debt.