Because people don't start off at scale, and because setting up a merchant bank can be a difficult hassle (more so if you're looking to accept multiple currencies), and because the cost of implementing features provided by stripe exceeds the amount lost in extra fees.
Once you hit scale it might be worth switching, but for many smaller sites Stripe is much more viable.
It's hassle. Much less than it used to be. It's also 2-point-whatever percent of all your revenue. The tipping point isn't as far out as you might think.
I'm not pretending it's for everybody, again, I'm just shocked that "oh we'll use Stripe because it's easy and cheaper than PayPal" is the group mentality (esp here).
If you're doing less than a hundred thousand a year in revenue, you will likely save in development costs what you would pay in fees (3% x $100,000 = $3,000 = ~week of development costs).
Depending on which Stripe features you make use of and would have to re-implement yourself it may even make Stripe more affordable up to a couple of hundred thousand in revenue.
That makes it very attractive for side projects or bootstrapped companies, and side projects and bootstrapped companies often grow in to larger things, and at that point, changing out the payment processing is low on the list of priorities.
If anything I think your estimation underscores the point that it quickly becomes worth the investment to shop for a cheaper payment option.
It always surprises me how quickly people are willing to adopt stripe without even making this calculation on their own and considering competitors.
I suspect since they are YC funded they give discounts to other YC companies which makes it a more viable
option and helps foster the ultra positive stripe sentiment you see on HN. I think there are a lot of people who eat up the hype without doing any real analysis of their own.
The positive sentiment is because they are a credit card processor that has a good API and supporting libraries. For some payment processors you are stuck with "here is our Java Middleware and this is the only thing you are allowed to use."
Yeah, I understand that's the root of it, but I've never understood how that positive sentiment remains so dominant when you start digging under the hood and realize that you're paying a percentage of your revenue for what amounts to a slick API or integrations. You don't need to be a financial genius to understand how little that adds up. It's always surprised me given the Hacker News crowd tends to like to dig into the details on most things.
Once you hit scale it might be worth switching, but for many smaller sites Stripe is much more viable.