bitcoin is absolutely the fastest way of transaction, if anyone want to transaction abroad.bitcoin could also minimize time duration and also other troubles that are commonly happened during withdraw money.but for making that process, sender and receiver both need to have btc wallet address.truly btc already has enough fame in worldwide but i can assume that most of people still don't know the process of use bitcoin and where to store it.so they select 3/4 days delay preocess, that's the simplicity of them.
Not quite, the confirmation of transactions on the Ethereum Blockchain is faster than the confirmation on Bitcoin Network, also, the transaction fees that users need to pay in Bitcoin are significantly higher compared to another crypto. But that should not be the reason for people to avoid Bitcoin, as bitcoin IMO is the most trusted cryptocurrency which really provides the decision for the users and makes them feel that they have freedom in their funds.
Other cryptocurrencies are regulated, Ethereum is somehow under the influence of Vitalik, but Bitcoin doesn't have any other outside factor that could stop its adoption as the people who use it has the power to dictate its future.