It is smart and it isn't, there is a reason second-hand tools can be cheap.

The problem is that when you are on a project, you need the thing right now, I am sure the author could have found what he needed for a fraction of the price second-hand, be he also wanted a working washing machine. Not spend a couple of weeks with dirty laundry waiting for the right tools to arrive. The local hardware store is expensive, but here, it is worth it.

You can avoid this problem by planning ahead, but it requires knowing in advance what tools you will need, and the answer is essentially "everything". That's how you find yourself with a home workshop. If you want a home workshop, that's certainly the right thing to do, but it takes space and a bit of investment, even with good deals. And you may find yourself with tools you will never use.

I know, my father left me with a bunch of quality tools he got for cheap. I am grateful for it, even though I didn't use most of them (he didn't either), some of them turned out to be useful, and the unused ones may find some use later. But it is also a good thing that I have a place for them, because that's a lot of stuff.

When you need them right now for half a day, like the author you rent them, and eventually plan to buy them.

Obviously I am talking about the expensive gear.

All too often second hand tools are worn out. There are some great deals out there, but tool restoration needs to be your hobby to make it worthwhile. My hobby is building things, not restoring tools and building the perfect shop. Nothing wrong with any of the above hobbies (I've restored a fair number of tools myself and spent a lot of time making my shop better), but you only live so long. Sometimes it is worth spending a few grand on a tool that will just work so you can get on with your 'real' projects.

Don't dumpster dive, go to a pawn shop or buy the tool your mechanic wants to sell off cheap. My mechanic friends go to 'estate sales'/garage sales in upscale neighborhoods and consistently picks up the set of SnapOns or decent DeWalt power tool for pennies on the dollar because some rich bro wanted to tell his friends about how he only buys 'the best' and only used it once. One pal grabbed a ~15 year old Milwaukee reciprocating saw for us$20 a while back...it looked like the prev owner never even opened the case.

OTOH...I guess that's really just trading the tool restoration hobby with the cruising yard sales for deals hobby.

Estate sales take a lot of time. Occasionally you'll find a treasure trove, but more often than not, they're just selling a dead person's junk. The best source of tools I've recently found was a local machine shop going out of business. I chatted briefly with the owner, who was retiring, and he could not find anyone else willing to learn the business/invest/take over. So he sold everything in his shop. Lots of good stuff.

Congrats on the score (why don't I ever stumble on those), but I suspect the ratio of 'yard sales with good stuff' to 'retiring from machine shop and everything must go cheap' is pretty skewed.