If your husband is unwilling to do any research himself, it would be a fool’s errand to “convince” him otherwise. Don’t try to make up his mind for him. You apparently hold separate investment accounts. Show him by example and let him come to his own realization - or not.
Brow beat him into a different position and you’ve got a marriage problem as soon as something goes wrong, and something is guaranteed to go wrong sooner or later no matter which investment strategy and vehicle you choose.
I’ve been following, make that learning Saul’s approach for about three years now. I lost my records from the first year in a computer mishap. I lost money, not a lot, but it was a loss my second year, third year I was up ~83%, more than made up for the loss the prior year. So far this year I’m up an astonishing 27% (just a little shy). I’m still a novice. I spend a lot of time reading and studying (I’m retired). I’m convinced that a portfolio of relatively few high growth really good companies is the single best way to make money in the market, but a lot of people can give you a gajillion reasons why I’m wrong, but all of them boil down to perceived risk. I’m willing to stomach the risk. Maybe your husband is not. He’s harboring more risk than he might imagine with bonds, but that S&P index fund is a pretty safe bet on slow and steady returns (BTW, this is what Buffet recommends for the disengaged investor).
Making money is good. Making a lot of money is even better. But you need to pay the price of admission. Accept the risks and engage in constant study. If you aren’t willing (or if your husband is not willing) to put in the time and effort, leave him alone about it and enjoy your life together.