You don't know your LTV, churn rate, or even if you have product market fit at the beginning so paid acquisition is sort a gamble. I think YC soundly advises that you get your initial customers in ways that are less scaleable and get to know them a bit before you turn on the firehose.
I have not attended the Startup School, but I imagine there's a lot of value in personally recruiting your first 20 or 50 customers. You get to talk directly to them; you get a chance (not easy, though!) to find out the real reason they stopped using it, etc.
I imagine you can talk to people that see your ads too.
Going after your customers looks great (honestly, I have zero successful experiences either way), but it is really hard for people that have a day job.
I built it from source to see if it was what I needed and it so scratched my itch that I paid the $20 as a contribution.
I don't do any professional development on my iPad, I just like having the ability to mosh/ssh back into my machines at home to run a script or push a quick edit to my personal github.
Anecdotally I've known 5 BMW owners, one was an older car (early 2000's), the rest made after 2010. The older one wrecked unfortunately, and all but one of the rest had mechanical failures.
Statistically they may not be any better or worse than any other manufacturer, but I still can't convince myself that their craftsmanship is any better. The koreans pride themselves in their craftsmanship too, and their cars are a third of the price.
Anecdotal too but the only car that has left me stranded ever was a bmw.
I love the older bmws for the driving experience but they require so much more maintenance than say a Lexus. The newer bmws meanwhile seem to be geared much more to the luxury market than driving enthusiasts (eg very few manual choices).
Ironically the least solid, least reliable car I have ever owned was a Toyota. After 8 years it was very poor. Other, older, cars I have enjoyed more reliability with have included a Honda, a Kia, a Fiat and a Lada.
(more anecdote) I've known a few people with corollas and drove them for a long time. All of them have been in pretty bad shape after a while. Engines running rough, lots of physical damage, struts and springs busted, little bits and pieces missing / not working etc. In fact all of them were pretty scary to drive and ride in.
In general they were all beaters that barely ran, but they ran. One corolla went for 2 or 3 years without an oil change and had 2 cylinders with low compression. Friend never got it fixed, but the car was still running (although with very low power). I actually think the general reliability of these cars leads to them being in worse shape. They're running so why bother to fix it. The owners also had a drive it until it dies approach, just generally took a long time to die.
I wouldn't use keybase where I need reliability due to their vague TOS (that came into effect around the beginning of this year): They can ban you from their service if they deem your actions outside their platform unacceptable.
Interesting, I had to check their ToS and found this which seems a bit vague:
"[...]use the Services to store or transmit any inappropriate content, such as content that: (i) contains unlawful, defamatory, threatening, abusive, libelous or otherwise objectionable material of any kind or nature" [1]
