DIY means DIY. You'd do it yourself if it broke. No different than a car, or lawn mower, or doing some construction on your home. Some do it, some hire out. Nothing is beyond learning, so the real question is do you want to DIY or not ?
I tend to find when I DIY something, I like the outcome and I feel proud of the accomplishment. Others might not. For a less affluent person DIY probably has a higher value too, (I'm guessing).
For some to save $1000+ it's worth it to DIY. For other's it might not be worth it. You'll see this same argument in other forums like the DIY audio forum, or the home theater construction forum etc... Same argument getting your car oil changed, rotating tires, or hire someone mow your lawn, etc... Anyone can probably do it, but some would rather pay someone else to do it for them. Not exactly the same, but you get the point I hope. Not going to be a universal answer.
I listed the cost above for my server. I think it's pretty close to reality. $3000 with drives. $1000 before software and drives. The main difference is you can't buy a Synology that will run windows applications, and have the power of an i7 CPU- even if you spend a few thousand more. So in some ways there is a choice there too. Synology is just storage solution, it's not a proper media server. A proper DIY media server will be both.
And - Drives will be a major cost either way. Especially if you run 20+ of them like me. Cutting the number of drives will shave off costs, I started with 6. It was nice to add some over time here and there as I needed, which is another bonus for the DIY FLEXRAID option IMO.
You can spend some now, and some more later when you need it. Drop half the drives or more, and one of the HBA cards, (even both?) you save like $1000 off my total price which is where I started. Easier to bite off some in chunks than all at once I think. It was for me anyways. I would have really struggled dropping $3000 all at once.