Regarding my experience with SPY-like investments.....
This is from my Google Sheets for VFIAX (Vanguard 500 Admiral Shares, functional equivalent of SPY-like funds) with .04% expense ratio. Not sure how well it will render, sorry in advance if you can't see it. In my case I had $1.2M DCA (dollar cost average contributions) $100K/month for 12 months beginning May 2022. The yellow line is $1.2M cash starting value (like the basis) and the red line is the value on a given day.
Notice Sept/Oct 2022 was not good for the market and the $1.2M went under water for a time being, same for Dec/Jan 2022/2023 and another little dip in Mar 2023. It also took a big dump in Sept 2023 so this is not for the faint of heart if you're watching your net worth whipsawing up and down like this.
As of late last week the $1.2M is at about $1.57M, a little over 30% gain in 21 months. I'm willing to take the risk associated with equities but this should be a lesson to anyone who is risk averse and cannot stand this type of fluctuation. In the long run this is probably going to be all good for me (I say probably because nobody can predict the future).
This graph self-populates using Google's GOOGLEFINANCE() function built into sheets. For propeller-heads interested the function looks something like this:
=INDEX((GOOGLEFINANCE("vfiax","price",A634)),2,2)
Where A634 is the Date entry I have in column A row 634 of the cell. Each cell in column A is just a date that increments every row. By the way, I'm not an Excel power user or anything like that. I'm all self-taught on Google Sheets only. I don't like using Microsoft Office at all.