How are people making 10k a month trading futures?

I trade with topstep and from my understanding you can have 5 funded accounts with them and after 5 payouts you get moved to a live account and are only allowed to have that one live account. Even if you max out 4 payouts at 5k on each of these accounts you get maxed out at 100k. After that you get moved to live and only have one account.

Are there other reputable prop firms where you can have multiple accounts to copy trade and never get moved to a single live account?

Once you are consistently profitable, what are the best firms to use where you can continue to scale up?