Vitalik came across a group of people who were trying to utilize the blockchain technology for a set of applications which would be used for financial contracts. He joined them and helped creating new features for the blockchain application. He also worked on several other blockchain applications and tried so hard to make them work because every little feature and functionality took enormous effort. He then realised there was no point in creating new features because people will keep on creating new use cases of blockchain and each time they will have to create new applications which can be time consuming.
The difficulty of creating blockchain based applications gave Vitalik the idea of attaching a programming language to a blockchain and having a single programming language, so everyone can easily create their own applications on blockchain. Ethereum now serves as an open source platform that allows anyone to build smart contracts and decentralized applications which run on network of distributed computers.