You also invite competition by selling/advertising your product. For any product, it's most probably one of the customers that'll go "I can make something better than this!" Also, if your income depends on absence of competition, that means that your product needs a bit of improving and that your business is fragile.
I may be wrong, but my assumption is that you are assuming putting your story on something like indie hackers is a lost marketing opportunity.
But I'd say a large percentage of successful small saas products are very niche and would not benefit in the least from talking about it in a public forum.
In my case, none of my customers would be reading anything like indie hackers so I have no reason to get the word out through those channels. It would just invite competition without returns.
