We as human beings, have been conditioned to put ourselves last. To feel guilty for wanting things. To learn to sacrifice and put our desires on hold. To work even when we hate it. We all have this idea from somewhere that wanting things is bad. We feel guilty for dreaming beyond our capacities. This has been a big issue for me too and I am in the process of releasing it.
When you work with the law of attraction, you have to find a way to feel good about your desire. This is when the limiting beliefs usually come up, and they have too, for me, in a big way. At this point, we simply have to make ourselves realize that it is really okay to let go and dream. When we hear that nothing is impossible, it is actually true. So, no, do not feel guilty for wanting something big! It is your damn right. Let go of this belief which is in no way serving you.
We humans are awesome beings who literally can attract whatever they want. It is your right.