You mentioned crypto and SEO, but the actual meat of your question involves Facebook, Twitter, and Google ads marketing.
I'm sure people have already answered you regarding Facebook and Google.
But let me expound on Twitter.
Twitter is very cheap right now because a lot of their big advertisers have left.
The downside with Twitter is that a lot of their traffic is bot-driven.
In fact, this is well documented.
Elon Musk has come up with a new program where active posters who get a lot of views get to share in the ad revenue.
This of course opens the floodgates to abuse.
That is why there are a lot of people running bots and all sorts of shenanigans.
Still, Twitter ads are cheap, and this is one of the reasons why there are lots of crypto ads on Twitter.
I think despite these setbacks and caveats, I still think in terms of ROI, Twitter might be worth advertising in.
It's pretty straightforward to advertise on it.
You can look up YouTube guides on Twitter ads.
The key is to actively monitor your campaigns to make sure that you're getting a positive ROI or you might need to change up your ads a little bit.