> If you have already accepted cryptocurrencies as the wave of the future, Coinbase provides enormous value. You can't do much in the crypto world without owning some cryptocurrencies, and they are the largest, easiest to use, and generally most trusted way to exchange $USD for Bitcoin or Ethereum.
If you accept it sure. However, the utility between the internet and cryptocurrencies are vastly different.
The internet provides light speed communication and seeing as we are a species built upon communication, communicating from days to fraction of a second which is also orders of magnitude cheaper (granted, not at the start but it got there and cryptocurrencies have not solved the scaling problem (cost) yet) is hugely beneficial. The benefits are completely obvious.
Cryptocurrencies provide you the ability to incentivize people you cannot trust to spend money to secure a network in the hopes that the cost of securing the network is greater than the cost of someone oversupplying your network and stealing your money.
Also, the benefits of control not being enforceable by a central authority is a bad thing in most cases and the few that are useful are outweighed by in pretty much every use case the billions of dollars it costs to run those computers to secure it.
It has been almost 10 years since the bitcoin network started, where is its killer use case?
Lastly, the billions of dollars spent to pay for the decentralized network to secure it are mostly payed for by creating new coins. At the end of the mining timeline, they will have to rely purely on transaction fees to pay for the costs to secure the network and the billions of dollars used to do so currently at a fraction of the scale Visa does will likely never outweigh the benefits of decentralization.
TLDR: Running decentralized nodes to recompute the same transactions to protect against untrusted nodes will always be more expensive than running each transaction on a single node on a trusted server.