A few different things would help.

First would be to be clear and unambiguous when it comes to building gas/oil thermal power plants in order to deal with the intermittence problem of solar and wind. Political strategies in wind and solar is built on trust, and people will quickly become unconvinced when politicians are dishonest/ambiguous about the requirements that is needed to support a grid with a high ratio of wind and solar.

Using fossil fuels as the reserve energy for when the weather is bad allows the producers of reserve energy to demand high market prices, to the point where a whole month in EU can cost as much as a full year. Even if solar and wind would put the grid costs to zero for 90% of the time, it doesn't make the cost for the consumer any lower if the fossil fueled "reserve energy" can increase their price by 10x. Selling solar and wind require some kind of solution here.

Reserve energy also want to be paid if they are expected to stand-by 365 days a week, which is a big reason why EU subsidizes to fossil fueled thermal power plants are not decreasing when the ratio of wind and solar goes up. That costs is then added as a grid fee/taxes, hiding the true cost. Paying first to keep the fossil fueled power plants warm and ready when solar and wind is producing, and then pay them a second time for whatever the market price is when they are producing is a very costly way to operate a grid.

And last is the transmission costs. Switching between multiple different energy sources depending on the weather has a high demand for a very flexible infrastructure in terms of transmitting energy from where it is being produced to where it is being consumed. In south of Sweden as an example, the cost of transmission infrastructure and the cost of reserve energy is now the majority of consumers electricity bill, with cost associated with production of energy being a small minority.

Solving those issues is what will convince people of the viability of wind and solar.