I don't get it either, but I would argue that it is a sport based on the below. This is what I got from Google which piggybacks off of the Oxford English Dictionary, I'm sure other arguments could be made based on other dictionaries definitions.
SPORT
An activity involving physical exertion and skill, esp. (particularly in modern use) one regulated by set rules or customs in which an individual or team competes against another or others
EXERTION
Physical or mental effort.
A Men's Health article reports you can burn about 420 calories over 2 hours which is what Harvard Health says you can burn while bowling
https://www.menshealth.com/uk/weight-loss/a37325926/study-finds-gamers-burn-420-calories-over-a-two-hour-session/
https://www.health.harvard.edu/diet-and-weight-loss/calories-burned-in-30-minutes-for-people-of-three-different-weights