The answer is that it often is not, at least for most people, most of the time. Eventually it will be the best payment system, but it needs to develop further, gain more adoption, and get over the scaling obstacles. Even so, Bitcoin is already the best payment system for certain use-cases, such as sending money across borders, or receiving money from someone you don't trust (which helps further in cross-border transactions).
Being trustless is nice, but how would I go about buying an online item if I can't trust that it won't arrive broken and that I can never get my money back? So then there will always have to be employees from whatever website to be able to handle claims and escrow reliably...which means if they go against you, you don't really have an option to go to a bank to get your money back (not that a bank is even helpful with that either).
See, you have mainly two options there, and as you said, banks already dont help much. If I were you, I would go with the more secure option, which is definitely bitcoin. Interceptions are impossible, and money is non reversible, and people can really thus veer away from deals at the last minute, once its done its done, and if both parties donot consent, it cannot be undone. Also, transactions are anonymous, faster and less transaction fees are required, atleast if you're not in a huge hurry to transact, where it becomes a problem sometimes, but the Lightning network is said to be able to overcome it.
Is is already as widely and easily usable as the traditional fiat that we use today? No. But will it be soon? Definitely Yes! Just think, paper currency has been around for hundreds of years, and even before that people used to barter, exchange stuff. This concept of cryptocurrency has just been up for 9 years, and its already a huge craze. So definitely it will catch up with fiat in the foreseeable future.