Capacity is scaling from the user perspective. If it costs $5 to send $5 worth of bitcoin because of transaction congestion and it's only processing a tiny fraction of what a single US credit card network does, the entire system is not scaling, regardless of how many nodes are running it.
Users don't care about scaling at all. They care about capacity only indirectly.
Scaling is something developers care about, but in the nascent field of cryptocurrencies there probably no single solution.
It should be noted that with your credit card example, however, that credit card networks charge a percentage of the funds transferred while in the case of Bitcoin it is instead a fixed fee. Should you instead have said that it costs $5 to send $5000 it would have been equally true but sounded quite different.
That Bitcoin as it is described in the whitepaper doesn't scale to even a single US credit card network should be obvious to any reasonably informed reader. That every participant in the network store everyone else's transactions forever has its limitations. Does that mean the technology is useless? No, it means the use case is different from credit cards.
It seems possible to build payment systems on top of Bitcoin that fills those use cases, and sidechains and payment channels are research along those lines. But just as crypocurrencies were a theoretical possibility twenty years ago, one should not expect working products too soon. It's not like there is a shortage of payment solutions in the meantime. For end users, credit cards offer a negative cost, so even then we should not expect the use cases to be identical.
There are many situations where it is a significant improvement:
* Fee is not dependent on amount of money you're sending. You can send $200M worth of Bitcoin to a company in China and it will only cost you $1.50, try doing that with a wire transfer.
* Transactions are "final": after 3-6 confirmations you can have a great degree of confidence it won't get reversed
* Compared to Western Union or MoneyGram, it's still faster and cheaper
But in its current state, bitcoin is definitely not a replacement for your Visa card when buying groceries at the store. Maybe Lightning will change that though.
1. I don't want to spend $200M worth of Bitcoin to a company in China. Something tells me that when you're ready to send that amount of money, bank fees do not even register in the expenses.
2. So, if transactions cannot be reversed, and I erroneously send money, or am tricked into sending money, I can't get it back?
3. So, BitCoin wins only when compared to Western Union and MoneyGram. Oh, what an achievement.
In it's current state bitcoin isn't a replacement for anything, really
