It starts well and ends terrible...that's usually how martingale works

But if it starts well, then why not stop and then do it again.

Build the balance in small increments or cash out each time so it adds up?

And eventually, you would just lose all your balance with a long losing streak.

Cashing out or building it in small increments doesn't help at all, it does not affect the variance and in some time, you will eventually bust.