The arts has one of the highest unemployment rates of any degree…and the price you give per painting is actually less than I would expect a person making a living off of their art would charge. A love of artists I know…are in IT. So though I understand your rant and how you perceive things to be…the grass is not always greener on the other side. That said…what is stopping you from pursuing art? It does not require a degree to be successful if you have the skills.
Also…mid 20’s sucks. That was the worst time in my life so far. Stick it out and figure out what works for you.
They make three wheeled bikes. Frequently they are set up as cargo bikes. Also some recumbent bikes have three wheels (sometimes double front, sometimes double back). I looked into a cargo trike when I was bike shopping but ended up with a cruiser with baskets and a trailer. A trike sounds like something that may work for your sister though!