I have a futurebit Apollo miner. Mines at about 3TH.
I bought it about a year and a half ago. Initially it mines about 1,000 sats a day. However, over time it kept going down. As of now it's averaging about 600 sats a day.
Why is it mining less? The halving hasn't happened yet
Also, I have been mining with Braiins pool the entire time, if that makes any difference
Learn to use a calculator
https://whattomine.com/asicThe more miners who mine Bitcoin, the less profit you get if your hashrate remains constant.
Look at the reports of large mining companies and think about investing in this business
https://bitcointalk.org/index.php?topic=5473513.03TH in Bitcoin mining has a very small hashrate, and I doubt that such mining is profitable.