Says a person who is certainly NOT a bicyclist. Pick up any Target bike. Put it down. Pick up my bike. Put it down. You will IMMEDIATELY feel the difference in weight. High quality frames are NOT made of the "same metals" as a big box retail frame. They are made of materials that are much lighter but still as strong. They are more flexible. They are more comfortable to ride. They have higher quality components that make them run better.How much you rode makes no difference on the quality. The fact that you brag about a paint job costing 3x more than a whole is even more laughable. If you have enough knowledge, any bike you can last that long. Anyone who actually wants to "get out a really ride" (aka, french people in tight shorts) wouldn't go to walmart anyway. Your bike is made from the sames metals as the walmart bikes mate. For most people who want to get around town, or to school, a walmart bike is just fine. The only difference is who assembled it.
Try going out on a 100-mile bicycle ride. After 25 miles, count how many retail store bikes you still see out there. After 50 that drops even more. By 60 miles, maybe 1% of the total bicycles out there are big box retail bikes. They simply do not provide the comfort needed for longer distances. They are also much heavier, meaning you have to put more effort to move them down the road than true road bikes.
My frame is now almost 26 years old. My father's is almost 30. Both are still in prime condition. I don't care how well you take care of a big box retail frame, 99% of them will be trash long before then. You simply CANNOT get a high quality frame at a big box retail store.