"Costs" doesn't mean real operational costs and so on. It is used as an accounting/business concept. Simply any .org customer has a yearly associated cost for having/leasing that .org domain.
OP's comment doesn't distinguish between different sources of that cost. (Sure, it has many components, the cost for the network, servers, development, security, backup, payroll, legal, accounting, some sales, marketing, audits/compliance, insurance, whatever risk premium, maybe off site backups, disaster recovery, outreach, bonus projects, 20% time, blablabla. Plus profits.)
Obviously everyone knows that the profits is the part that will now grow much larger. And eventually the .org customers will ditch .org because of that. But OP is right, from .org customers' standpoint, it doesn't matter why, it just matters that their costs will rise and as soon as it crosses a point (cost of switching becomes less than the cost for remaining on .org) folks will leave.
OP's comment doesn't distinguish between different sources of that cost. (Sure, it has many components, the cost for the network, servers, development, security, backup, payroll, legal, accounting, some sales, marketing, audits/compliance, insurance, whatever risk premium, maybe off site backups, disaster recovery, outreach, bonus projects, 20% time, blablabla. Plus profits.)
Obviously everyone knows that the profits is the part that will now grow much larger. And eventually the .org customers will ditch .org because of that. But OP is right, from .org customers' standpoint, it doesn't matter why, it just matters that their costs will rise and as soon as it crosses a point (cost of switching becomes less than the cost for remaining on .org) folks will leave.