The banks have some of the best information in the world on where interest rates will be going in the future, very highly paid econometricians and proprietary software.
Banks wouldn't offer fixed rate loans if they weren't coming out in front on the deal
Individuals may periodically do better than if they were on a variable rate if they're lucky, my parents were on 8% fixed from '72-mid90s when they paid it off. However, the bank already has it worked out that they balance fixed rate loans against the interest rates they're paying to depositors, so they're making a defined profit regardless. On average, fixed rate loans are a money maker.
I'm an economist, and I don't go for them - variable all the way!