Just to speculate: Perhaps self-sabotage allows someone to maintain a high self-esteem ("I'm great at everything") while ignoring subjects which are difficult ("I'd be great at that, too, if it weren't for X").
This self-delusion has direct benefits; people with high self-esteem are more attractive. But it also makes it easier to ignore a pursuit, which perhaps encourages people to spend more time on fewer pursuits, and with greater enthusiasm. Such specialization may help a male stand out from other suitors.
A few years back, I signed up to be a counselor at a wilderness camp in Southwestern Colorado. Hiking. Climbing. Camping. Living in a log cabin without plumbing at 12,000 feet for three months. I was very much not in my element.
I had a great time. No one there knew me before, so there weren't any preconceived notions about who I was. It was liberating.
However I also was at the bottom of the "coolness" ladder among the counselors, because I had no background in the outdoorsy skills that "mattered" out there.
So doing things that I normally would shy away from was good for me. But yes, as you say, it screwed up my "game."
This self-delusion has direct benefits; people with high self-esteem are more attractive. But it also makes it easier to ignore a pursuit, which perhaps encourages people to spend more time on fewer pursuits, and with greater enthusiasm. Such specialization may help a male stand out from other suitors.