Those older examples suffered from the &quot;double spend problem&quot; where you could spend the digital currency twice (or more).  Kind of like cheque fraud.<p>The Proof of Work part of bitcoin (the part that consumes all that electricity) creates a consensus record so that if double spends are performed, only one of them will stick.  Now double spends are a &quot;feature&quot; called &quot;replace by fee.&quot;<p>Preventing double spends is worth millions to investors, so that&#x27;s why it continues.