Getting the fuel home, where it can be used domestically as well as for tanking-up starships, could provide an early pay-off for developing a fusion propelled starship.
A Helium Market
The original "Daedalus" starprobe design had two stages. A Stage Two, by itself, would be well suited to being a deep space freighter, able to carry payloads of up to 500 tons at very high speed. Uranus is nearly three billion kilometers from the sun and Earth, thus traveling there, and back, requires a high-speed vehicle.
A Stage Two freighter could carry itself, with an empty mass of 500 tons, to Uranus in 70 days for just 114 tons of fuel, and then bring back a load of 614 tons using about 254 tons of fuel. Of the return load, 114 tons would be used to return the empty tanker to Uranus, while 500 tons would be used for starships and the terrestrial energy market.
A starprobe might launch by the year 2100 and if world energy demands continue to increase at their historic rate of 2.5 percent, then by 2100 about 14,000 tons of deuterium/helium-3 fuel-mix would supply the world's energy demand per year, adding an incentive to develop the gas-mines of Uranus.