Many aspects have been taken into account by the originator of Bitcoin including its anonymous identity, basic aspects that are only available in 21 million Bitcoins including its decentralized nature. When Satoshi introduced Bitcoin to the public, at that time he was 100% sure that his creation was perfect. lifting the limit on the number of bitcoins could increase miners' income in the short term, but it would highlight one of the main arguments for investing in Bitcoin, namely its scarcity.
One of the attractions of investors starting to come to the Bitcoin industry is because of its fixed supply, lifting the limit on the number of bitcoins could remove a fundamental driver of Bitcoin's value proposition. In theory this change would increase miner income in Bitcoin, but this change would cause a huge price drop resulting in miner losses in fiat.
The hard cap on Bitcoin is secured from alteration by its incentive structure and governance mechanism. The entities that govern Bitcoin's ruleset have significant incentives to fight a change to the hard cap because of the network's architecture, but those who wish to change it have no power over the network.
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Can Bitcoin's hard cap of 21 million be changed?