Train travel is very popular in Switzerland. It would not be that popular if it was to expensive. One could argue that it is the other way round, that in other countries train travel is to cheap, and that as a result the money to provide a good quality service is not available. In Switzerland public transport is so good that it is not necessary to offer it at bargain basement prices to attract customers.
Also the way public transit is priced here it is more expensive for occasional use, but a lot cheaper with regular use. This is intentional.
The alternative to using the SBB is to have a car, which, as you will find out, is actually more expensive…