You know why it is not fun? Because the person creating the bicycle put life, energy, sacrificing pleasure and comfort, sometimes up to exhaustion in order to hold the space, to get the tools  and to create it. One wanting to use it must help first the creator not for the object itself but for the humanity in them both, so that the creator can keep going after they have made something that makes your life more simple, beautiful, comfortable, pleasureful or whatever helps or give meaning to you. It is not theft but it is not fair neither. It is just predatorial. Like capitalism itself.