Satoshi Nakamoto did not intentionally limit the block size when he first created Bitcoin. At that time, the block size is around 1 to 2 KB on average. Some people thought that an excessive block size is a waste of computing resources and is susceptible to distributed denial of service attack (DDOS attack). Therefore, Satoshi Nakamoto set the block size limit at 1MB to ensure the security and stability of the Bitcoin network. Since there was only a small number of Bitcoin users then, the transaction volume was small and there was no network congestion.

But with the constant increase in Bitcoin users and trading volume since 2013, problems like network congestion and rising transaction fees occurred. Bitcoin transactions could sometimes take several days to process and Bitcoin transaction costs could be as high as tens of US dollars. Consequently, there have been numerous proposed scalability solutions since 2013. Some proposed increasing the block size limit while some proposed removing redundant information from the block. However, none of these solutions gained widespread acceptance and the issue of Bitcoin scalability remained a heatedly debated topic. In August 2017, Segregated Witness, SegWit, was activated and the data processing capability of a single block increased by 1.7 times. SegWit is the first step towards the SegWit2X solution to increasing salability.