Because investment theses aren’t as simple as “thing X is a good investment”. You don’t start with the assumption it’s a good investment and try to disprove it

Because investment theses aren’t as simple as “thing X is a good investment”. You don’t start with the assumption it’s a good investment and try to disprove it. You do the opposite, and with some sort of analysis. It’s not that batteries are good or bad. It’s whether this amount of capital invested in batteries with this company and this business plan at this cost of capital is a good investment.