How do I (29F) tell my partner (31m) that he is not as handy as he thinks he is?

Hi all!
I have been with my partner for just over 3 years now and this problem has popped up enough that I am not sure what to do about it.
Basically my partner considers himself an "amateur handyman" (his words). He likes to put furniture together, change the oil on the car and do simple home repairs. Normally this is fine.
The problem is anything beyond basic repairs he believes he can do. But his skill level isn't really there. This becomes an issue when we have a repair needed done and he will insist on doing it himself, but since he doesn't have the experience or the know-how, he will have to "teach himself" using YouTube videos. Sometimes this is fine. Other times the repair can be a bit shoddy, and when I ask if he can "tighten it up" he will snap. Or the repair will be so outside his skill level he will get frustrated and let it languish while at the same time refusing to call a repair man because "he can do it." He also frequently encounters the problem of not having the right tools, which means we spend money on tools that get used maybe once, or are not the correct tools for the job anyway.
This all came to a head when we ordered our new vented dryer and I gently urged him to pay for installation as well, but he INSISTED he could vent the dryer out the wall. I was very skeptical and pushed more forcefully to pay for installation and he pushed back. I lost. Well turns out my "amateur handyman" does NOT know how to vent a dryer out a wall and he got so frustrated because he "doesn't have the right tools" he went to take a nap instead of fixing it. So now I am at home with a dryer that doesn't work, and a big urge to say I TOLD YOU SO.
I don't want to talk to him right this second because I am quite riled up, but when I calm down I want to have a conversation with him about being realistic about his skills and limitations. He is normally lovely, easy to talk to, and willing to compromise about almost anything else, but this seems to be a big sticking point. I think being known as "handy" is really important to his identity and if he feels like I question his abilities he gets hurt and frustrated. I also don't mind him doing basic repairs and if he wants to improve his handyman skills I am happy to support that as well, but sometimes I just want the repairs done and dusted and not all this waiting around and tool shopping. I have tried to have this conversation in the past and it always devolves into a fight. I am quite a direct communicator so that may not be helping. Any advice on to how to have this conversation?
TLDR; My partner attempts repairs beyond his skill level because he likes being known as handy. How do I talk to him to let him know that hiring a repairman does not take anything away from his handiness and sometimes it is necessary?


Source.