How much would sales be if photocards and bulk buying are not allowed?

they would have their sales reduced in at least half I think. after mots:7 bts never managed to get those numbers again and it's because they did at most 2 versions, it wasn't because of lack of hype (at least with BE).

less than 100 albums per group ( mostly company staff and family members )

I think the sales will reduced to 20%
no point of buying without the collectibles

I will just pirate / download the album

More than half of sales would be slashed instantly. If bulk buying was discouraged by having no photo cards or other perks and you couldn't steam or fudge sales numbers to prop up a groups popularity. Then 99% of kpop including BTS would not be as visibility popular as they are now.

Maybe the decrease will depends on how many members they had and how many concept that are made into poca?

Like if it was a 4-5 members, then at the barely minimal it would be reduced 4-5 times (if it was only 1 concept photos)

If the group is, let say 9-13 people then it might had a bigger reduction...

A massive decrease, maybe half or more per group. Kpop fans but albums as if they're pokemon because of photos lol

BTS had already shown how they would sell with two overly expensive versions that no one would bulk buy. If they played like their peers then they would have already surpassed seven million by now.