Ethereum’s ecosystem is the biggest in crypto by a wide margin. The majority of DeFi, nearly all NFTs, most stablecoins by issuance, and the entire Layer 2 landscape all sit inside this category.
The aggregate figure at the top of this page is closer to a rough indicator of “Ethereum’s gravitational pull” than a strict market cap, because most non-Ethereum tokens have some form of Ethereum representation and many are cross-listed. What it captures well is the scale — Ethereum has more tokens, more protocols and more activity than any other chain.
For the background, see our what is Ethereum guide and the Layer 1 sector. Data below is live from CoinGecko.