The short answer to this is that domain hacks tend to be harder to sell to end users as you have to find an end user that would be interested in building their entire business around a domain where a lot of people are going to very likely mistype it.
For example, not too long ago I was looking for VPN’s when I came across a website that has the domain “hide.me”. I visited the site and then forgot about it till a few days later when I remembered it and decided to visit it again. As you can guess the first thing I typed in was “hideme.com” and not surprisingly I landed on a completely different website. It took me a while of searching around on Google to find the website and that’s when I realized their domain name was a domain hack.
I personally don’t get involved with buying/selling domain hacks as they seem like a lot of risk but I do know of a few people that have managed to sell a few domain hacks to start up firms for low 4 figures so there is hope out there. If you plan on getting involved with domain hacks just beware that they can be much riskier than normal domains and you REALLY need to be able to a skilled salesman as there not easy to unload.
Hope that helps.