30 years isn't really a good thing, here.

I've been coding for more than 40 years, and I probably only took security seriously, in the last 25 or so.

In fact, in Ye Days of Yore, we often deliberately coded in unsecured stuff, for convenience.

Look at some of the old Apple Systems (pre-OS X), to see some stuff that would make secops people defecate masonry.