It's not, geez y'all keep saying shit without actually trying it. Me and my friends do this while working out, our veins are more than his and we can hold them for a 7ish seconds before they go away. Stop thinking that it'll pop or rhat a paper cut would kill him.
You need low body fat percentage and muscles, people say you need good genetics but that's just not true, it looks more insane if you have good genetics but you can still get a unbelievable amount with normal genetics
These veins come from working out and heavy lifting. When I tried it I was able to see a bunch of veins because of my lifting. So if you don’t workout, don’t be surprised that it didint work. (Not being mean just saying)