There are legit uses that enterprise companies are using today, but they are few and far between in comparison to day trading/speculation/etc. For example, moving money from different currencies usually requires foreign exchange fees which can be hefty - whereas if you buy some stablecoin in a local currency and then sell that stablecoin in the currency you want to have in your bank account, you pay tiny transaction costs and thats it. This is a real problem for companies who have operations in tons of countries, and have to manage bank accounts and local entities in all of those countries. Imagine reducing your profit by 1-2% just because you want your profits in ireland instead of mexico. Stablecoins make that into <0.5%, which is many millions.

https://a16zcrypto.com/posts/article/stripe-bridge-acquisiti... has some examples