Turnover is not a spending limit
Required turnover adds the value of bets, including bets made with recycled returns. It is different from the deposit and from the money you can afford to lose. A small deposit can still be attached to a large turnover requirement.
Why the loss estimate is limited
Turnover multiplied by one minus RTP is a simplified theoretical loss estimate for completing the entire turnover at a fixed return. It does not model running out of funds, changing games, fees, bonus enforcement or a cashout cap.
Keep your own limits first
A number produced by a calculator is not a recommendation to gamble. If the requirement conflicts with your time or spending limits, declining the promotion is a valid decision.