I understand that pot odds is ratio between the pot amount and the call size. Stated differently it's the ratio Win amount : Lose Amount. In terms of Expected Value if the Win% of your hand is more than the pot odds then calling the bet will give you positive Expected Value.
Specifically pot odds would be this ratio (Pot amount + Opponent bet size) : (Your bet size)
This is assuming Win amount = Pot amount + Opponent bet size. However why don't we discount the money that the player contributed to the pot prior to calling the current bet (i.e. the blinds, any preflop bets, etc.).
This would mean Win amount = Pot amount + Opponent bet size - Our money already in the pot
and Lose amount = Your bet + Our money already in the pot. So adjusted pot odds would be:
(Pot amount + Opponent bet size - Our money already in the pot) : (Your bet + Our money already in the pot)
This gives drastically different pot odds depending on our prior contribution to the pot. Is there an explanation why people choose to ignore this? What am I missing here?