Oh you are super right about customer acquisition. That matters a ton! You should see some of my other videos that touch on that.
But I do think picking an idea from direct experience seems to work extra well, having funded hundreds of startups and seen what works and what doesn't.
That's not the case, however, with acquisition channels (a topic I write extensively about [1]), or your audience (they come with pre-defined beliefs/behaviors that are hard to change.)
Having this in mind, it makes more sense to focus first on analyzing a) The audience b) The channels through which you can reach to them. Once you get enough knowledge about these 2, you can create a pretty good startup idea WITHIN these constraints.
This is why people have invented things like market-product fit or product-channel fit [2]. I'd like to add that you're more likely to succeed if you FIT your idea TO the channel/audience, rather than doing the reverse.
Would love to hear other perspectives on this topic.
[1] https://firstpayingusers.com
[2] https://brianbalfour.com/essays/product-channel-fit-for-grow...