They aren't slow and expensive, it's very cheap to send and receive money from any place to any place within minutes. Lots of people in my region use money transfer services. Btw Bitcoin is not a very good competitor in terms of speed and price because when transaction fees are high, Bitcoin fees can be more expensive than the fees of money transfer services and in terms of speed, Bitcoin sometimes need at least 1 hour because many companies don't accept transactions with lower than 6 confirmations.
Bitcoin blockchain and Bitcoin transactions are good for people who care about security, safety and privacy of their assets and transactions. If the main concern is transaction fee, Bitcoin blockchain is not the best choice.
It depends on main concern, people will have different choices and if any newbie still wonder why Bitcoin blockchain is good in security, let's read some documents.
How many Bitcoin confirmations is enough?Btw altcoins like XRP and Litecoin are very fast and cheap solutions compared to Bitcoin. Bitcoin shines in decentralization.
If you want cheap transaction fee, let's go with Ripple, Litecoin, Dogecoin and I personally are favorite with Litecoin and Dogecoin that are Proof of Work altcoins while Ripple is not.
Litecoin and Dogecoin blockchains are not secure like Bitcoin blockchain, but they're better than Ripple.
https://howmanyconfs.com/