I think this grow in user base and trading volume it rather caused by the fact that durign Q1 bitcoin pumped from 29k to 61k.
From today's binanace quarterly burn report:
"In Q1 2021, Binance recorded growth of 260% and 346% in traded volume and users respectively,"
https://www.binance.com/en/blog/421499824684901944/15th-BNB-Burn-%7C-Quarterly-Highlights-and-Insights-from-CZSo despite the fact that coinbase is growing very fast it does not mean that it is growing against binance. Binance might in fact grow even faster.
And binance is also starting to dominate etherum (not yet but those number are prmising):
"1. BSC reached as much as 4.9 million daily transactions (as of April
. That’s 300% more than Ethereum’s all-time high in daily transactions.
2. The total unique address count on BSC has reached 64 million in just eight months. For comparison, Ethereum is at 148 million.
3. Currently, 450+ projects have been built on top of Binance Smart Chain.
4. BSC played a significant role in growing the number of active dApp wallets (+639% in Q1 across all blockchain platforms), bringing in an average of 105,000 daily active wallets, compared to 458,000 daily active wallets for the entire industry."
https://www.binance.com/en/blog/421499824684901944/15th-BNB-Burn-%7C-Quarterly-Highlights-and-Insights-from-CZ