At a high enough level, I’d use creation on either gold or diamond. Might be hard to sell a 5x5 block if either but you’d make good money if you could. Or just become a human 3D printer and sell off the things you make.
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Wish is an easy one, since it can be used to cast most of the other spells talked about here
Clone, immortality without any of the normal downsides (I can choose to die still and don't need souls or any bs like that)
Identify and go pawn shop hunting and the like
Really most divination spells would be solid for stock market manipulation
Enchantment spells for manipulating the corporate ladder, or getting into politics or something (mass suggestion in the really any political nexus, geus for more targeted things, modify memory, etc).
Healing and revivification spells and sell my services to the elite, bring back the dead, speak to loved ones, etc. Clone works well here too, especially since it has age manipulation.
Charm, Modify Memory, Illusions, Disguise Self, ...
Always make yourself look way richer and important than you are, smaller millionaires and celebs will flock to you and the bigger fishes will try to use you but they can't because... repeat from the start.
Plan 1: Raulothim's Psychic Lance. By the time I get to take that spell, I must have had at least one ASI so I'll just take metamagic adept for subtle spell. I just have to know the name of the target and be within 120 feet of them (240 if the second metamagic option I take is distant spell), and it's pretty close to a guaranteed kill vs. a commoner, no murder weapon, and nothing showing that I was there.
Plan 2: Clone. Claim that it's some revolutionary stem cell rejuvenation therapy and sell it to the super-rich. (Though I might make it fail accidentally if it's someone like Murdoch or Kissinger. Payment in advance, no guarantees, and I'll do it on international waters.)
Not very experienced, but I'd probably True Polymorph dirt/Steve Huffman into some gold and sell it.
Suggestion. I could really use a better job with better pay.