Investing in anything in them is a huge mistake. It's like investing in improving black and white tv at a time when color tv have 10% market share and growing 50% a year.
Car companies have no choice but to sell ICE for a while. The demand is still there and they can't convert to EV production overnight.
Yet, the winner of tomorrow will be companies that convert to EV quickly and without going bankrupt. Spending $1B on non-EV technology is not going to help GM do that.