Everyday I see lots altcoins on Binance increase 10-40%, then I look at BTC dominance and it stays relativly the same around 44.3%. Are smaller altcoins just draining Ethereum, XRP, ADA, NEO and other big coins of their marketcap?
There will always be coins going up and coins going down.
The coins that you see on Binance on the top risers are usually coins with extremely low market caps that will have very little to no overall affect on the actual altcoin market share when compared to bitcoin. The major altcoins either go down to compensate or do not move at all. They could even go up in certain circumstances where the entire altcoin market is going up.
Usually bitcoin dominance will stay relatively the same unless there is major news regarding bitcoin or major alts. Small alts don't matter much in the greater context, but you can certainly make a profit off trading them.