Bonzo Banana

Huge number of advantages to folding bikes some obvious some less so. One advantage not always mentioned is their ease of sizing so a family can own one and pretty much all members of the same family can ride the same bike, both adults and children. Great if you need a bike which people will only use occasionally or you simply don't have room to store multiple bikes. One bike shared by four members of the family means you are only maintaining one bike between you.

They tend to be low geared compared to most bikes so are easier to ride regarding physical exertion and you get more time to enjoy the scenery.

Steering is often more twitchy because of the smaller wheels, you can maneuver around obstacles more easily. Congested traffic for example.

The small wheels are stronger and more durable and less likely to go out of true.

They are allowed on public transport as normal baggage/luggage

Most folding bikes are designed for the rider to have an upright position while riding so the rider is more aware of vehicles for greater safety. Admittedly there are some folding bikes with drop handlebars but fairly rare.

The ability to fold and store your bike in the workplace means not only is your bike much less likely to be stolen but I have seen many bikes chained up where bikes have no weather protection outside workplaces etc and the bike drivetrain is corroded and in poor condition which means more maintenance and replacing parts will be far more frequent.

Like anything though folding bikes work for some but not all but you do see people who would obviously benefit from a folding bike. I think folding bikes only have a small percentage of worldwide bicycle sales somewhere between 2-5% but it feels like that figure should be higher and many more people than that would benefit from one.