Please argue reasonably. The logical derivation in the PoC has been described in detail, see pages 5 to 6. Please read this passage carefully and check out what you didn't understand about it instead of simply dismissing something as being “worthless”.
There are many logical reasons why the rate of punishments should be even lower, see for example page 10. We always considered the worst assumptions for SavAct in the calculations. Even then, SavAct saves the sellers a lot of money.
Regarding your concerns, please have a look at this chart from the PoC:
Table 3 - Fraud possibilities in comparison if no agreement can be found. Successful fraud is marked using red underlined font.
When using direct payments with cryptocurrencies there is a high risk that the seller does not deliver the goods. After all, the seller already got his payment. When using SavAct however, neither party benefits from scam. The risk of the seller won’t be exactly 0% anymore, but still very close to it and because of the increased trust, the seller would be able to increase his sales figures over his competition.
If you ever paid with cryptocurrencies before, and did not receive your purchase, you would definitely appreciate having SavAct as an option.