The spell does say what happens.
...if the object is moved more than 10 feet from where you cast this spell, the glyph is broken, and the spell ends without being triggered...
I would apply this to breaking the object in half or scratching the glyph. As for it it being too easy to disable, keep in mind the glyph is nearly invisible. You're not going to spot it just walking past. You have to be looking for it, or at least investigating the area. It's not going to be easily found.
There's also the idea that you can set one of the triggers to be if the glyph is tampered with so it does go off if someone tries to disable the glyph.
Yes you can cast spells that target self into the glyph
Spells that target "self" meet all the criteria for allowed spells
Glyph of Warding describes all the limitations for which spells can be stored in it:
You can store a prepared spell of 3rd level or lower in the glyph by
casting it as part of creating the glyph. The spell must target a
single creature or an area.
There are no other limitations.
Since spells that target "self" only target a single creature explicitly they meet the single-target criteria.
Targeting - specific beats general
One might wonder how a "self" spell would be targeted upon the glyph being triggered, but the spell covers that as well:
If the spell has a target, it targets the creature that triggered the glyph.
Does a spell that targets self have a target? Yes. So, according to the spell that self spell will now target the creature that triggered the glyph.
Specific beats general. So this supersedes the restriction that self spells only be able to target the caster.
In order for this spell to function as designed, it necessarily supersedes the normal targeting rules for spells with its description.
It's worth noting that this spell also necessarily supersedes several other major general rules (Spellcasting effects, concentration) with its specific effects in order for it to function.
Thus, there is absolutely no reason why this isn't fully allowed.
The spell's wording has changed
It is worth noting that an older version of the spell description began with the line:
When you cast this spell, you inscribe a glyph that harms other creatures.
However, the spell has been the subject of errata, and the first line now says:
When you cast this spell, you inscribe a glyph that later unleashes a magical effect.
This appears to be a confusion point.
Best Answer
Technically? Not Quite, but close.
The Glyph trigger cannot specify an individual. The best you can get is to specify creature kind, alignment, and described physical characteristics (height and weight, etc.) If you get to the point where the description no longer accurately describes you, you would be unable to trigger it. If someone else who fit the description happens to say the command word before you (very possible if you make the area large enough) then they'd be the one to get the benefit. Still, these things can be worked around enough to cheese it.
Practically? Depends on how much the DM is willing to let you get away with.
This is pretty clearly abusing a fuzzy point in the rules. As such, it is pretty much exactly the sort of thing that Rule Zero was designed for. Indeed, there are all sorts of exploits for Glyph of Warding that you can come up with. Your DM can and should give a ruling on this for their own game, based on the needs of that particular game, and probably based on things like how clever you're being, how entertaining it is, and how hard they think you're likely to try to abuse it in the future.
Pragmatically? Think about whether or not you want to open that can of worms.
There are a lot of DMs out there that won't pull cheese until you start pulling cheese. There are a lot of enemies out there with access to 3rd level spells. PCs generally get into combat a lot more often than random potential enemies do, which means that said enemies can afford to spend more time building up an arsenal of "just say the command word" Glyphs of Warding, for both themselves and their allies. You might want to think twice before trying to bring this particular exploit into being.