But with freetrade the costs are basically gone, other than stamp duty and PTM levy for large trades. You can trade in a size of £10,000 and only have 0.5% stamp duty and the spread to make up. Stocks swing 5-10% weekly, so it’s fair game to make a couple of hundred pound a week doing this.
Personally I do not swing trade, since I invest for dividends, but I could very easily sell my whole portfolio and start swing trading with £78,000 (which will not move the market whatsoever). I see a lot of £100,000+ trades on the LSE order book, must be the big banks doing this. But I and many others would be happy to collect a few percent off a £100,000 every week for sure.