I've spent $17.64 on on-demand usage in cursor with an estimated API cost of $350, mostly using Claude Opus 4.5. Some of this is skewed since subagents use a cheaper model, but even with subagents, the costs are 10x off the public API costs. Either the enterprise on-demand usage gets subsidized, API costs are 10x higher, or cursor is only billing their 10% surplus to cover their costs of indexing and such.

edit: My $40/month subscription used $662 worth of API credits.