最近Robinhood金卡出现了发DM和Credit Karma来绕过WL的奇技淫巧。正好趁着这次热度来分享一下我对于他们盲盒的数学分析。
先上结论，对于有办法MS/有机 刷满的用户来说，每次开盲盒的期望净利润达到$23，净赚啊净赚。
假设
下面是我的假设：
- 假设MS的成本是3%（如果是有机，这是你不开盲盒也能拿的3%收益/其他信用卡的收益）。
- 假设你单笔金额能刷到当前buff的上限（通常在$300～500)
假设完毕，下面列出term里的概率和buff品类，以及我的计算：
计算
| 盲盒奖励 | 概率 | 计算过程 | 收益 | 期望收益 |
|---|---|---|---|---|
| 100,000 Points | 0.001% | 100000*0.01 | $1,000.00 | $0.01 |
| 10,000 Points | 0.200% | 10000*0.01 | $100.00 | $0.20 |
| 7,500 Points | 0.300% | 7500*0.01 | $75.00 | $0.23 |
| 5,000 Points | 0.500% | 5000*0.01 | $50.00 | $0.25 |
| 2,500 Points | 1.000% | 2500*0.01 | $25.00 | $0.25 |
| 1,500 Points | 1.500% | 1500*0.01 | $15.00 | $0.23 |
| 1,250 Points | 2.000% | 1250*0.01 | $12.50 | $0.25 |
| 10% cashback on next grocery purchase ($500 cap) | 5.000% | 500*(10%-3%) | $35.00 | $1.75 |
| 5% cashback on next grocery purchase ($500 cap) | 8.000% | 500*(5%-3%) | $10.00 | $0.80 |
| 10% cashback on next automotive refuel purchase ($300 cap) | 2.000% | 300*(10%-3%) | $21.00 | $0.42 |
| 5% cashback for 30 days ($10,000 cap) | 0.250% | 10000*(5%-3%) | $200.00 | $0.50 |
| 5% cashback for 1 week ($2,500 cap) | 2.000% | 2500*(5%-3%) | $50.00 | $1.00 |
| 10% cashback for 24 hours ($3,000 cap) | 0.500% | 3000*(10%-3%) | $210.00 | $1.05 |
| 5% cashback for 24 hours ($3,500 cap) | 6.000% | 3500*(5%-3%) | $70.00 | $4.20 |
| 4% cashback for 24 hours ($3,000 cap) | 17.000% | 3000*(4%-3%) | $30.00 | $5.10 |
| 15% cashback on your next purchase ($500 cap) | 3.000% | 500*(15%-3%) | $60.00 | $1.80 |
| 10% cashback on your next purchase with your mobile wallet ($500 cap) | 4.000% | 500*(10%-3%) | $35.00 | $1.40 |
| 15% cashback on next restaurant order ($500 cap) | 5.000% | 500*(15%-3%) | $60.00 | $3.00 |
| 10% cashback on next restaurant order ($500 cap) | 25.749% | 500*(10%-3%) | $35.00 | $9.01 |
| 5% cashback on next restaurant order ($500 cap) | 16.000% | 500*(5%-3%) | $10.00 | $1.60 |
结论
加总期望revenue可得$33.04，已知盲盒成本为$10，净利润$23.04。
一些TIPS
- Robinhood有玩不起的先例，把3%降低到1%，各位悠着点别触发风控了。最好别骑车。
- 就算被限制成1%，如果前面各个buff的10%/5%是写死的，而不是随着3%降低到1%而自动降低2%，对于这个盲盒流似乎也没有损失
- 最好不要同时开多个buff，因为everything 4%/5%这种buff会导致其他所有类别相关的buff全部失效。如果有些deal有时效性就拿不到了。
