Market making dealers in govt bonds provide liquidity to different types of fund managers. For instance, hedge funds, insurance funds, pension funds. All fund managers must preserve and/or grow funds. Pension and insurance funds are referred to as "real money" as, unlike hedge funds, they don't use broker dealer credit to leverage positions. They are also highly regulated compared to hedge funds, so can't use derivatives, go short or generally pursue riskier strategies. So regulation prioritises capital preservation over growth, for obvious reasons. Real money funds tend to be far less technically sophisticated than HFT or systematic trading hedge funds. So they get charged more, in the form of wider spreads, by dealers as they go in and out of positions. Why might they go in and out of positions? One reason would be tracking a govt bond index monthly. The bonds in the index may change, so to continue tracking a real money trader has to buy some bonds and sell others once a month. That real money trader will get a worse price from the dealer than a hedge fund trader who has far more live market data and pricing tech to assess the prices offered by dealers.