YOU SAID:

I bet that people who build rivers make bank.

INTO JAPANESE

私は川を造る人々が銀行を作るに違いない。

BACK INTO ENGLISH

I must be the people who build rivers build banks.

INTO JAPANESE

私は川を造る人々が銀行を建てるに違いありません。

BACK INTO ENGLISH

I must be the people who build rivers build banks.