Sentience, self-awareness, consciousness, etc.,those are terms signifying a bridge between "technical" information theory and the psychological and social realms.
Those are just as real, only far less predictable and not as easy as programming.
They're also far more important and consequential.
The "far more important and consequential" thing you're touting is your ability to make decisions based purely on vibes. And not even consistent, broadly agreed-upon vibes like "murder is pretty bad". It's vibes of the most vile variety: "sentience is what I decided sentience is".
An average internet user is sentient, but a 1996 Nissan ECU isn't. Why? Because I said so. Tremble before my might!
A "proper" definition represents the objective truth about the matter. You denying such a truth to exist is simply due to you preferring to act unimpeded by it.
Acting against ethical constraints doesn't become OK just because there are no laws to punish you.
Ethics tells you about real-life consequences of your actions on other people. Before any laws take effect.
In effect, you propagate moral relativism. You want to do as you please, because you said so and fancy the spoils at others' expense. People trembling before your "might".