I'll try to answer in the order of your questions/comments:
He eventually decided to wait. Congratulated? Well, IMHO, based upon all my input, he waited and was able to get back to about even after today. That process of waiting requires some conviction and a bit of guts. And, by the way, the Chinese/ US trade deal hasn't even materialized yet even though I believe there is more upside to come but that doesn't matter in his case. As long as he is happy to get back to breakeven then he can sleep soundly.
He now realizes that you don't put "house" money at risk when trying to buy a home. That is the lesson here, in addition to the lesson that you MUST be a long-term investor to play the game.
Let me ask you something; do you think Warren Buffett and others like him are LUCKY? To me, lucky is hitting a lottery ticket for $10 or more. The odds are astronomically against you. In stock investing, you have a higher chance of success due to the company/fund/etf research possible. Sure, sometimes you need to wait years but in the end you can reap the benefits.
In investing, you set goals. In this case, he was happy to get back to even so you have to move on and learn from the experience in your investing mindset. FWIW, I have lost thousands of dollars on speculative plays in my younger days. Now, from those experiences, I stay away from IPO's and early investor plays. On the other hand, I was an early investor of Microsoft and have made hundreds of thousands but in that case I had/have substantial data in which to evaluate.
This was really not an "investing pitfall." This guy just made a mistake: you save for a house; you don't invest for a house. Sure, he like anyone else, can make huge investing mistakes in the future. You develop a set of parameters and adjust them as necessary as you move on in life to compliment your life changes (ie. jobs, kids, college funding, retirement). Hopefully, your choices will reap the benefits you expected OVER TIME.
In the end, it's the averages over time that don't lie. I'll take 9-10% (adjusted to 7% for inflation) every day over anything else. Hedge fund managers can play the higher risk game for others.