Yes and no. You're losing a lot if you're making money to rush production instead of making production. You're not losing a lot by using money to grow more effectively.
While you spend ten times as much, the efficiency in your rate of growth is more important than money unless you're actually using it for other expenditures and don't have enough. In the early game, the initial expansion of your empire can be greatly improved, and even into the late game, it's a major advantage to rapidly spend your way into a state of productivity on newly acquired planets. You can easily knock a couple hundred turns off the accumulation of production to build a new planet up into an effective generator of resources.
It may even be advantageous to skip production improvements entirely, and use money to improve highly specialized worlds, that simply don't have enough room to justify making them efficient to upgrade themselves. The right combination of improvements and bonuses could end up being far better than the money spent to build it up.
I would never simply spend money to buy things without cause though, it truly is a waste of resources if you're not getting some gain from it. It's best saved for emergencies and upgrading the fleet.
