Bad software is an avalanche, waiting.
“We don’t need to worry about that for Version 1, let’s defer that to <version n>”.
“What can we get away with for what now?”
“Do we really need to worry about Cross Site Scripting? Who would want to hack us anyway?”
“Just get this bug fixed. Next time we build a new feature we’ll do it right.”
“Our customers don’t care about whether or not the software is good or bad, they just want it to be flexible.”
Once the avalanche starts, that’s it. There’s no going back. Sometimes that avalanche is launch day, sometimes it’s when the New York Times reviews your product. Sometimes, it manifests as the bankruptcy the company files because of a security breach.
You can get away with bad software for a while. But only for a while.