How does my family support someone who doesn't want to do literally anything?

So I have a sibling who is working towards their late 20s and has no HS diploma or GED, can't drive, spends all their money on w33d, works a 1-day-a-week job, plays video games all night, and sleeps all day.

This has been their routine since puberty, and no amount of pleading, punishment, encouragement to seek mental health help, or just conversation has helped.

At the end of the day, this was a parental issue, something that should have been solved in youth, but now we're well past that.

I went out and bought them clothes, self care items, hygiene items, etc. Spent well over $200 hoping this would assist in feeling good enough to even conquer one thing and it hasn't.

My mother tries to get them to go and practice driving with her, has offered to do driving lessons at a school instead and we get utter refusal.

We have a local college my other sibling and I are going to, this college has a GED program that is very cheap and we have a bus line that picks up in front of our house and goes straight to the college regularly, 2 years have gone by and nothing.

I know they need therapy/psych help, but they just refuse due to them having to be the one to make appointments.

Kicking them out is not an option, they have nowhere to go and we won't be making anyone homeless, but what is there then to do? We're met with some much aggression and blame when we bring anything up that I'm just so lost.

I know it stems from embarrassment, anger, disappointment, depression, and so on but after someone is 25+ years old what am I to do for this grown adult? Does anyone have any advice at all that could help in getting them moving in the right direction? Even baby steps are something.