I'm an indie dev and I have been running Casting Call Club for about 7 years now and it's grown entirely word of mouth, hitting 700k sign ups just this month. When I launched Reforge, it was the same story. Entirely word of mouth. Bootstrapped to $10M per year.
Mostly, I'm of the opinion that you do not need ads to build a successful product. In fact, you probably shouldn't run ads.
"Product-led-growth for B2C or bottoms up B2B is the way!" - me, who is often wrong.
So when I see things like this on Twitter, I get confused.

Is this word of mouth, or is this using bastardized paid ads, or is this just low-quality contest frenzy?
From Levels' own data, he spent $10k and returned $0 in revenue directly. He did not publish all the data around it, like impressions, clicks, and shares that since made him money from this.
Curious, I thought I'd give it a go. My Twitter profile has significantly fewer followers (2.7k) than Levels (150k), so I knew that my impact would be less, even if I gave away $10k. Plus the product I was promoting was a brand new product that A) has no traction at all and B) would have a smaller ARPU than RemoteOK. So I scaled the price down to $300.

Even though I have a sample size of two, the retweet count seemed to correlate roughly with the Dollar amount prize being awarded. So my $300 reward turned into roughly 300 retweets. Levels' $10k rewards was around 10k retweets.
It's not reflected in this image, my Twitter followers increased around 130 as a direct result from this tweet. I think this was largely due to the fact that I run @CastingCallClub (11k followers), which retweeted this tweet.
This type of tweet would be a promoted tweet, where I would be charged based on billable action. In this case, it would have been link clicks, not expands, retweets, likes, impressions, etc.
The charge per action would have been $1.68 to $10 per website click, so the cost for this tweet would have been: $189.84 to $1,130
Overall, I think it turned out pretty well given my limited reach.
No. This felt like a big distraction when I could have been building word of mouth features that would've yielded better results.
Really interesting to read, and funny to try that approach.
I could imagine you have access to less analytics doing this compared to ads?
Nevertheless, thank you for sharing your experience 🙌