Help me figure out my parent's finances? (TQQQ question also)
Less glamorous than some of the $20m trust fund questions but I'm here (on a new account for 100% privacy) to ask for some help with my finances. This is a r/personalfinance kinda question but I see a lot of people give dumb advice there and my risk tolerance is a bit higher because I'm heading to a pretty high-paying career myself so I'd love to hear some WSO advice.
Me: Junior at target school heading to large UMM/MF PE fund (10 billion + latest fund).
Parent: A bit shy of 50 years old. Moving out of my home city for another job. Selling house worth ~275k. Income is 75-80k. Has about 100k in a 401k and 75k in additional investments/savings. Total net worth around $450k.
To provide a bit of extra context around this; this parent is in an engineering profession, has an advanced degree, and is on a career path that should max out at 120-150k within the next 5 years. The reason their current pay is so low is because they were a stay-at-home parent for almost 20 years, and only started working ~3 years ago which made them restart at the bottom of the totem pole. Got taken advantage of in a divorce so don't have as much as you'd probably expect. I trust this person to save and be responsible with their money, which they 100% are. They are super frugal anda year already while maxing out their 401k as well in a low COL city. Their only financial mistake was raising me instead of working, and putting too much trust in their partner, which I don't fault them for.
I have full control over my parent's money. We have trust that goes both ways, and while they are great at not-spending, being frugal, etc, they don't know anything about investing and stubbornly refuse to learn so I just do it. I am 100% voluntarily planning on financially supporting them if possible. Whenever I propose this they shut me down, because I imagine it must be embarrassing knowing your kid is going to have to support you financially and must be frustrating knowing that, but I personally realize (although they won't admit it yet), that the math doesn't check out without me supporting them so I'll likely do it anyways. Another thing to note is that I believe this person's wish is to retire abroad in their country of origin, where COL is much cheaper. You could live like a king while withdrawing 30k/year. I think this makes it a lot easier to plan for retirement. The fact that I will likely end up supporting them (and me being an only child) means that this money is as much mine as much as it theirs, so I am heavily personally invested in maximizing its future value, because its money that I won't spend later on and potentially some could be passed onto me later.
The Question: The only real question I guess I have is what to do with the cash we get from selling the house. Should be around ~260k net of fees. Do I just throw it all in SPY right now. The person still has ~15 years to retirement so technically the money should be safe there over a 15 year time period... right?
Also, should I diversity their investments in any way (~$350k not including the 401K)?. RN all their money is in equities with a bit in fixed income. Like I'm not even sure what sort of additional risks would be worth taking. But investing in RE, angel investing groups, etc? I feel a bit aggressive with the risks I want to take, especially because taking risks with this money now could be really good for me in the long run, but I want to make sure I'm being safe as well.
Also, TQQQ? Should I just throw 10k into it and let it sit for a decade? I kinda got the idea from a WSO post a couple days ago so probably not the best idea but heres the logic: I view it as a. If threw 10k into TQQQ 11 years ago at inception, it would be $1.8m now. While losing $10k is bad, it is not LIFECHANGING. On the other hand, getting $2m IS lifechanging. This is the idea. Thoughts?
Any other general advice for managing their money?