Because Cosmos has some serious advantages.

First and foremost, it is a blockchain that allows different blockchains to be linked together. Cosmos allows you to build a decentralized application or run your own blockchain as quickly as possible, at minimal cost, and still be able to interact with other blockchains within the ecosystem (Interchain) and external blockchains via so-called decentralized bridges.

Cosmos is blockchain 3.0 and here's why:
It was created to solve problems with scalability, usability, and problems that are associated with interoperability limiting developers to only one network. Open source tools like Tendermint and the Cosmos SDK allow developers to quickly build secure, scalable, and interoperable blockchain applications and eliminate the limitations of interactions inside and outside the network.

For example, a Tendermint-based blockchain can communicate with an ethereum blockchain that is not part of the Cosmos ecosystem. Tendermint is a kernel that is connected to the ABCI (Application Block Chain Interface), which allows creating applications in any programming languages. Thus, by building blockchain on the Tendermint kernel, developers can focus all their attention on their own product without worrying about consensus and security, developing applications in any language they want.