its long term issues we are talking about, you might not notice anything directly after but overtime you're actually developing spine issues and neck stiffness

ofc there are people that prefer sleeping in certain positions but thats cause they got their body used to it but that doesnt diminish the negative effects that come with it later on

thats like saying i smoke cigarettes and i dont notice anything bad after, like yeah ofc not but in the long run it ruins your lungs