There's lots of short-term trading strategies that can work without L2 data. I know 2 people running short term strategies making 7 figures consistently who don't rely on L2. It's a dogma in certain high frequency trading firms that L2 is necessary for profitable edge (since that's a core part of their edge). That said, most profitable short term traders do rely on L2.
7-figures per-year with annual returns of about 100% (not including the capital they use on margin), which is fairly typical for a proprietary short-term strategy
