Hello Bob. Blockchain as such isn't to be mixed with a cryptocurrency like Bitcoin: blockchain is simply the technology (like a database if you will) that enables the cryptocurrency to function.
In terms of your first point, as far as I'm aware the application of Bitcoin hasn't yet reached a stage of liquidity, and easy trading for small-value items. Due to the heavy "gas fees" (transaction fees to validate each transaction on the network), small amounts wouldn't make sense especially in light of the volatility of the Bitcoin value. You couldn't really buy a coffee and realize you paid much more than what the price was a minute ago, because for some reason Bitcoin's value just dipped.
There are however improvements upon Bitcoin such as Lightning Network that seek to remove some of these barriers.
On the second point, gains from trading in cryptocurrencies is taxable if capital gains are realized. I believe this also applies when trading across cryptocurrencies...on the grounds that they are treated as commodities.
Tim wrote a previous piece about using cryptoassets like cryptocurrencies, to secure loans of other assets as a way of being tax efficient.
Platforms are now emerging which allow you to deposit and invest in cryptocurrencies like Bitcoin, and then be able to borrow against the value of those assets you hold on those platforms.
In terms of engaging going forward, personally I treat Bitcoin and Ethereum as risky, volatile experiments rather than "investing" in the purely rational sense. I think it's a long-term play with many ups and downs that aren't predictable or necessarily logical.
We have just seen this now with the higher inflation in the CPI yet a hit on the Bitcoin price (before Musk's latest statements) - which runs counter to the "anti-inflationary" thesis of Bitcoin supporters.
If one sees the underlying Blockchain technology as having wider applications though, then currencies are but one area of interest. Arguably so far the most promising one, but decentralized applications are being developed on the Ethereum network (using Ethereum the cryptocurrency).
It's hard for me to gauge where this is going though; lots of uncertainties and in spite of the claims made, some clear central influence (be it by mining operations 70% of which are based out of a few mining farms in China, or by one single individuals and their highly-influential tweets...)
