Or you use the savings from not having a car to have the pizza delivered.
Or, in less car-oriented places, you walk to the pizza place to pick up the order, just like Laverne and Shirley would walk over to the Pizza Bowl in a fictional portrayal of 1960 Milwaukee.
A large watermelon? Really? How many times has that happened to you? Do you leave the watermelon in your hot car while you work the rest of the day? You also can't easily carry a windsurfer on a bicycle, so might mention that too.
But in answer to your question, if you are going to be carrying things on your bicycle, put some baskets on, like https://waldbicyclebaskets.com/products/582-rear-basket-blac... or https://www.femmecyclist.com/how-to-carry-groceries-on-a-bik.... Then you can carry a pizza and a watermelon at the same time.
As an unattached male, are you going to eat that entire watermelon on your own?
As to becoming attached, you'll find there are women who don't want a car-centered life.
So does the "entire western civilization" include Europe? Or just the US? And are Asia or Africa somehow less centered around the personal (ICE/electric) vehicle than Europe? (Especially if you include mopeds and motorcycles.)
The culture of bike-riding has existed since the 1890s and the invention of the safety bike. It faded after WWII, especially in the US due to government subsidized white flight, but elsewhere as well. It started re-emerging in some places, like the Netherlands after the 1970s Stop de Kindermoord movement.
"Protestant ethic for hyper-individualization"? You'll find that Catholic countries are also car-centered, the Protestant Nordic countries didn't have the American sense of hyper-individualism, and Weber's ides of the protestant ethic was that dedication to hard work and sacrifice is noble in its own right. Perhaps you're thinking of the frigidity of rugged individualism, as Mamdani described it?