It's important for clean energy to be cheap because that creates an economic incentive for people to invest in switching.
The good news with renewable energy and battery storage is that we're basically there. Texas which produces lots of oil also produces lots of clean energy. Because oil refineries require a lot of energy to refine their fuel. And of course using your own product at a premium when clean renewables do the same job would be madness. Think about it, the very companies that are expecting others to buy and burn their fossil fuel are investing (heavily) in renewable energy because that's cheaper than using their own cheap supply of oil and gas for the same purpose. It's more lucrative to sell that than to use it for them.
That's why records are being broken with amounts of solar, wind, and battery coming online on a regular basis. It's cheaper. So, people do more of it as fast as they can scrape the funding together to do it.
Fusion if it happens at all is probably going to be really expensive for quite some time. Nuclear has the same problem. Clean but just super expensive. And slow to plan and execute. You need to decide decades in advance that you need it in order to have it ready. Most reactors coming online this year (hint: not a lot) were planned when solar and wind were still expensive (1-2 decades ago). In other words, they probably did not take into account current price levels of new clean energy. In terms of profitability these things are kind of dead on arrival. Fusion faces the exact same challenges. It's not completely hopeless. But we need 1-2 orders of magnitude reduction of cost per energy generated this way.