Think about a low-cost index fund as a proxy for investing in the entire economy. Warren Buffett calls it "extreme diversification" and recommends most investors (including professional money managers) take this approach.
I use the CORE and EXPLORE approach. Money I can't afford to lose is in my CORE portfolio (a diversified basket of low-cost index funds [also called "asset allocation"]) and the Dividend Aristocrats mentioned above. Money I can afford to lose, but don't want to lose, is in my EXPLORE portfolio, such as crowdfunding, options trading, and real estate finance (note investing).
My Dividend Aristocrats were in my EXPLORE portfolio when I started out. But they are now working successfully, so I consider them part of my CORE portfolio. My goal is some day, the investments currently in my EXPLORE portfolio will become part of my CORE portfolio as I become competent in managing them successfully.
I also owned a home once (33 years) and glad to have had the experience. Owning a home has its rewards, but it's also a full time job (which is how I know I would not enjoy managing rental property). I'm not sure if I want to own another home again, but the possibility remains on the table.
My only regret is not starting to invest when I was in my early 20s. Looking back on my life, the opportunity was there right under my nose and I ignored it. But rather than playing the coulda, shoulda, woulda game with myself, I just suck it up and move on.