I disagree with that guys opinion.
You can never own too many tools. I find that the money I've saved over having it contracted more than pays for the specialty tools. I keep most of them but have done very well selling some after I'm done.
I sold my tile saw after 1 project. I'll hire any tile job done from now on. I don't care for that activity.
The best one was in 2005 I put in a boat and RV storage lot. Several different contractors bid +- 40K for the dirt work and crushed concrete.
I bought a brand new JD5103 with loader and box blade. Spent 17K on that and 16K on crushed concrete. Saved a bunch on that project and still enjoy the tractor to this day.
It did take substantially longer to get it done but I wasn't in a big hurry.