You already know why but let's put the numbers on it, because the fix depends on which of the two costs is biting.
At $4.20 a percentage fee is not your problem. Coinremitter at 0.23% takes a cent. NowPayments at 0.5% takes two. Neither of those is visible against a 90 cent margin.
The killer is anything fixed. Here is what a single $4.20 order costs on each rail, using what I paid in the last week of February:
| Rail |
% fee |
Fixed cost |
Total |
% of order |
| BTC on-chain |
0.01 |
0.41 |
0.42 |
10.0% |
| ETH L1 |
0.02 |
0.94 |
0.96 |
22.9% |
| USDT on Tron |
0.02 |
0.12 |
0.14 |
3.3% |
| BTC Lightning |
0.01 |
0.00 |
0.01 |
0.2% |
On-chain Bitcoin at your ticket size is not a payment method, it's a donation. Whatever gateway you pick, the decision that matters is which chain the customer pays on, and most of them will pay on whatever the checkout shows first. Reorder the list and half your problem goes away before you change providers at all.
Caveat on my own numbers: one week, and February was a quiet fee week on L1. In a busy one the ETH row gets worse, not better.