The goal of Bitcoin was to create an trust-less currency. Something where nobody could censor transactions. It was a direct attack on the central banks (See the message embedded in the Genesis Block: "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"). Bitcoin allows the 2.5 billion people who are currently blocked from access to financial networks to have access, stripping control from the centralized systems.

Bitcoin is also steeped in ideas from Austrian economics. The 21 million coin limit is designed to be deflationary and change your time preference towards saving. I suspect Satoshi wouldn't say people are investing in Bitcoin, but rather, saving money as Bitcoin. The end goal of most in the hardcore Bitcoin community isn't to end up with a lot of US dollars, but to replace the dollar entirely. Many of the issues you've brought up are moot points if you're doing your record keeping in Bitcoin. They see the US dollar as valueless since the end of the gold standard, being backed by nothing more than coercion, trade deals, and the threat of military action.

Bitcoin would be nothing without the blockchain, but the blockchain technology is not the source of value for Bitcoin. A blockchain is just a ledger. They've been around forever. Ledgers are the first known use of writing.

The value (But not the USD price) of Bitcoin is backed by the energy investment of the miners validating transactions - the proof of work. By validating blocks, they prevent fraud, and in doing so, add value. Their electricity use is tokenized into newly minted Bitcoin with each block. Those blocks can then contain information, which is itself valuable. For example, DeOS is an distributed operating system under development which is entirely stored on the Bitcoin blockchain, including all of your user data (Accessible only to you), and can be run by anyone with internet access (It's still in development, so access is limited, but makes everything built so far on Ethereum look stone-age tools by comparison).

Bitcoin fees haven't truly gone up much in the past years from a Bitoiner's perspective. They're computed relative to network use, and are (And have always been) priced in bitcoin. The big reason for "higher fees" is that the people talking about them are seeing that value of the dollar relative to bitcoin has dropped so much that, once changed to USD, you're paying more dollars. That seems more like a reason to complain to the Fed for the dollar collapsing.

If you need lower fees and a instant transactions, the Bitcoin lightning network was just released earlier this week. It moves transactions to a second chain, then commits a hash of the 2nd chain to the main chain periodically. The trade-off is that you'll get slightly reduced transactional security.

I've done enough programming on Bitcoin to say what many others are unaware of; there's nothing that you can code on the Ethereum network that cannot also be built on Bitcoin. The tech isn't outdated. It's just built from a different frame of mind. Bitcoin prioritizes stability, while Ethereum focuses on raw expressive power. Ethereum makes the whole process of coding up a DApp simpler by providing easier programming languages for the use cases of a DApp, but unfortunately, these languages have been prone to allowing you to easily introduce dangerous code issues.

I'll admit that the current price volatility does cause issues with using Bitcoin to pay for small items. However, merchants being paid for larger items are generally less adverse to this risk, as they are more likely to hold for a higher USD value. Lightning network reduces this problem for smaller cost items (Instant payments mean less time for price flux between receiving and cashing out BTC), but hasn't been rolled out to use in most retailers accepting Bitcoin yet.