Space of Bitcoin Blockchain – Bitcoin Stack Exchange

Not every user running a full node keeps a local copy of the entire blockchain. Most users probably run their node in pruned mode, which means they only need a few gigabytes to store the UTXO set (a set of transaction outputs that could be spent in future transactions).

The reason this is safe is that a pruned node needs to actually download and validate the entire blockchain when initially synchronizing. However since the UTXO set is enough to validate new transactions and blocks, the blockchain itself can then be discarded.