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.

Hence a good strategy is use martingale and stop while you are ahead.

It is possible, although slim to lose out in the short run, there is still a small risk to bust.