Olle P :
But there's supposed to be only a finite amount of BTC to be mined in total! At some point all are created and further mining is futile since no more can be created!
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Transactions <> Mining.
Transaction fees would become (already are?) way more profitable than doing any mining at all.
I don't see how transaction fees (from a non-miner) could somehow reach somebody who's mining while not creating new coins.
Tx fees are awarded to miners...
When a miner finds a block (which happens approximately once every 10 minutes), they are awarded with new BTC (12.5 BTC per block at the moment, reduces by factors of two over time, eventually going to zero sometime around the year 2140), as well as the Tx fees associated with all the transactions included in that block.
Philosophy, or rather "the way it's being used", yes. But the technology (program code) behind it hasn't changed, right?
The code itself changes, Bitcoin core software is still being updated. In some cases, where people don't agree on an update, a hard fork is created. This is how Bitcoin Cash (BCH) came into existence. Supporters believed in increasing block size in attempt to increase transaction throughput, as they felt that not doing so favored treating BTC as an investment (i.e. digital gold) rather than a transactional currency. Many people disagreed with the proposed changes, and that group continued without the changes (Bitcoin), with a new fork with the changes implemented became BCH.
A big factor preventing BTC from functioning as cash is that the technology can't really handle that sort of volume (at least for now), due to limitations on transaction throughput (and as a result slow transactions and high Tx fees). The "philosophy" aspect I mentioned is that at least some people in the BTC community seem to think that those limitations aren't really issues, or at least not issues that are a high priority to address. In contrast to someone who wants BTC to be used as digital cash, for whom issues of scalability and throughput would be considered a top concern.
I also think the deflationary nature of BTC lends itself more to a store of value than a transactional currency.