I love what your cousin did, but there’s a big difference between that and beekeeping. Not even the same types of bees. The bees kept for honey / wax production and pollination are more like livestock than “nature.”
The problems that beekeepers have been seeing the last 10 years may be in part a problem of genetic diversity.
Thats not the main story though: Wild bee populations (along with nearly all other insects) are having a bad time too. Habitat loss and pesticides are thought to be the reason.
Beekeeping may even be a contributing factor to some wild populations decline due to competition over ever more scarse resources.