The downvotes and no reply are a pretty good example of what's wrong with less wrong. Someone who is genuinely confused should not be shooed away then insulted when they ask again.

First of all remember to do and be what's best. If this doubt is engendering good attitudes in you, why not keep it? The rest of this is premised on it not helping or being unhelpful.

External reality is much more likely than being part of a simulation which adjusts itself to your beliefs because a simulation which adjusts itself to your beliefs is way, way more complicated. It requires more assumptions than a single level reality. If there's a programmer of your reality, that programmer has a reality too, which needs to be explained in the same way a single level one should as does their ability to program such a lifelike entity and all sorts of other things.

More fundamentally though, this is just the reality you live in, whatever its position in a potential reality chain.

If we are being simulated, trying to metagame potential matrix lords' dispositions/ ask for favours/look for loopholes/care less about its contents is only a bug of human cognition. If this is a simulation, it is inhabited by at least me, and almost certainly many other people, and there's real consequences for all of us. If you don't earn your simulation rent you'll get kicked out of your simulation place. Qualify everything with "potentially simulated-" and it changes nothing. "Real" just isn't a useful (and so, important) distinction to make in first person reguarding simulations.

and/or you could short circuit any debilitating doubt using fighting games or sports (or engaging in other similiar activities) which illustrate the potential importance of leaning all in towards the evidence without worrying about the nature of things, and are a good way to train that habit.

Also, in this potentially simulated world, social pressure is a real thing. The more infallible and sensitive you make your thinking (or allow it to be) the more prone it is to interference from people who want to disrupt you, unless you're willing to cut yourself off from people to some extent. When someone gives you an idiotic objection (and there are a lot of those here), the more nuanced your own view actually is the harder it will be to explain and the less likely people will listen fairly. You could just say whatever you think is going to influence them best but that adds a layer of complexity and is another tradeoff. If you're not going to try to be a "philosopher of perfect emptiness" taking external reality as an assumption is the most reliable to work with your human mind, and not confuse it: how are you supposed to act if there are matrix lords? There's nothing to go on so any leaning such beliefs (beliefs which shouldn't change your approaches or attitudes) prompts is bound to be a bias.