Thematic investing has its pros and cons. Just don't ignore valuation.Anyone who bought stocks related to artificial intelligence (AI) a few years ago is sitting pretty today. Anyone who sat on the sidelines is likely experiencing the fear of missing out, otherwise known as FOMO. It can be difficult to sit still when it feels like everyone is getting rich, and you're not.Many readers are likely looking at AI stocks as we near the end of 2025 and asking whether there are still gains to be had. Can you still ...