High budget AD items on a jungler - who has one of the lowest incomes in the whole game. The idea is not very appealing for me.

Then the guide is very... unappealing to read as well.

To put it simply:

Thresh is not a carry-style jungler based on his kit, but that's precisely what you're building him like.

As a result, you've built items which only do not synergise with his whole kit, but puts him in danger - when he lands a hook and goes in, all he will do is die before he will kill anyone. That's if you can even afford your items in the first place...