this is sort of a simplistic take. not everyone has the goal of making money on every single trade. say I buy some security from you, not because I expect it to

this is sort of a simplistic take. not everyone has the goal of making money on every single trade. say I buy some security from you, not because I expect it to go up, but because I believe it is uncorrelated with my other holdings. you realize a capital gain, and the value goes down the next day. did I lose? not really; we just had different goals. edit: maybe a better example. I am confident in $SPCE over the next six months, and I want to open a long position. I want to slightly reduce the risk though, so I also buy an OTM put from you. $SPCE keeps going up, so the put expires worthless. we both won here. you collected the premium and I got into a long position that I wouldn't have otherwise.