Is it dumb to do doordash for more income if I make good money now?

I was talking to my sister who does doordash, that’s her only job since she’s in college. She said she makes about $200-300 a week.

I currently work long hours and make around $1500 a week. After paying all of my monthly expenses (mortgage, car note, groceries, phones, utilities, insurances; etc.) I have about $1000 leftover a month, sometimes more sometimes less.

I told her I think im going to start doing it as well to have more money to put away a month, even if its just a couple hundred dollars.

She is now saying it would be very dumb of me to do this since I make “good” money now and it would just take away from my down time. She seemed very against me doing it and keeps telling me its a dumb decision to add more to my work load.

Isn’t it a smart idea?? If you work for doordash, do you make good money for a side hustle?