Bitcoin supporters mostly agree that Bitcoin has no intrinsic value.
Au contraire. I'll contend bitcoin has intrinsic value in the form of its supply limiting algorithm, construction and design.
That doesn't make it intrinsically valuable though. The value comes from everyone agreeing it has value, that's extrinsic. The difference is that a business that generates cash flow has intrinsic value regardless what people's common opinion is on the business. Whatever cashflow it produces for shareholders is the intrinsic value because it's value which doesn't come from an opinion. Bitcoin doesn't have intrinsic value because it's value comes entirely from people's perceptions of what it is worth.
If Bitcoin’s price continues to rise, we’d be spending more and more energy to mine it.
The majority of electricity for bitcoin mining is derived from surplus energy. Which does not affect or strain existing grids.
The productivity of mining hardware increases over time due to moore's law. While the energy consumption of mining hardware decreases for identical reasons.
Power plants scale to energy demand. There is no such thing as surplus power. When more energy is demanded by miners or for any other reason, power plants scale to meet the demand and use more resources to do so. Further, your second point ignores that fact that power consumption goes up over time because more and more miners are brought online to compete for blocks, far more than offsets due to efficiency improvements. I don't necessarily buy the arguments against bitcoin because of energy consumption anyway, but your points don't prove it.