Here's a little horror story for young investors. I have a nephew who is 39 years old now. His best friend went all in during the dot com bubble. Phil had amassed over $900,000 in investments that grew exponentially from a modest start. He was going to get out when his investments reached one million. Well, they never got there and Phil lost almost everything hanging on hoping for a rebound. He was in his 20's, single and he took a chance. He's doing fine now but he still regrets not getting out when everyone told him to cash it in.
Not getting shell-shocked by losses is key. I've had some pretty big losses. Overall, I'm up however. It's a difficult mentality to take. Knowing you will lose loads of money in short periods of time, but gain over the long run.