Everyone is different when it comes to bras and hence why there are is a dizzying array styles and models to suit any taste. Everyone's breasts are as different and unique as they are. Men's breasts included. There is no one size fits all.
For those with smaller breasts, A-C cups, then a pull over sports bra type or a bralette type might be all the support you need. If that's the case, you are not alone. Many women fall into this same category and wear this type of bra everyday for the same reasons you do. But if you have D or D+ size breasts, as some of us do, or have more breast tissue or your breasts are more dense, hence more weight hanging off your chest, a pullover or bralette may not give enough support for everyday wear, containment or shaping. More "traditional" bras such as underwire or seamed cup or engineered bras like molded or spacer cup bras work better for support, containment, shaping and to a slightly lesser extent, modesty (high beams, pokies, nipples showing). Just because your "junk" maybe different from a woman's, doesn't mean your breasts are different than a woman's. They are not. Your tissue is made of the same tissue as a woman's. Men normally do not have the proper ratio of hormones to have development as women. But some of us do. As with women, everyone has different levels of development. It just happens to be that most men do not develop pronounced breasts, just like a small number of women who do not develop pronounced breasts as well. And many of them are as distressed about being flat chested as we are about development and for the same reasons. Society says women have defined, pronounced breasts and men are flat chested. The reality is some men have very pronounced, feminine breasts and some woman have flat, manly looking chests, not even needing to wear a bra. Neither diminishes who they are because they don't fit the societal normal. And chest support should not be defined by gender, but need. If a woman feels she doesn't have enough breast development to warrant wearing a bra, then that's her choice. If a man has breast development and finds that wearing a bra is beneficial, then that's his choice and no one should care in either case. But we know that isn't what happens in both cases. I have been discriminated against about buying a bra because it was for me (a male) and not my wife (a female). But all I am trying to do is to be comfortable and have good body image with what body I have. It has nothing to do with gender. It's a physical thing. And I am sure flat chested women are pressured to get a "boob job" to look more "womanly" just like we are pressured to have reductions to look more "manly". Frankly, it's no one's business. Just my opinion.