[RPG] Do you waste sorcery points if you try to apply metamagic to a spell from a scroll but fail to cast it

Casting a Spell at a Higher Level
When a spellcaster casts a spell using a slot that is of a higher level than the spell, the spell assumes the higher level for that casting. For instance, if Umara casts magic missile using one of her 2nd-level slots, that magic missile is 2nd level. Effectively, the spell expands to fill the slot it is put into. Some spells, such as magic missile and cure wounds, have more powerful effects when cast at a higher level, as detailed in a spell’s description.
—Player's D&D Basic Rules, page 78

Since the slot is 3rd level, the spell is 3rd level. Since the spell is 3rd level, 3 points are needed.

Note that, for many spells, a higher level slot does more damage, as well. Ray of sickness does two extra dice of damage as a 3rd level as opposed to 1st...

The failure is possible if trying to cast a spell with a level higher than you can cast from a Spell Scroll.

Spell Scroll, DMG pg.200:

If the spell is on your class’s spell list but of a higher level than you can normally cast, you must make an ability check using your Spellcasting ability to determine whether you cast it successfully. The DC equals 10 + the spell’s level. On a failed check, the spell disappears from the scroll with no other effect.

The general rule for scrolls in the DMG pg 139 is "Any creature that can understand a written language can read the arcane script on a scroll and attempt to activate it.", however, the specific rule for Spell Scrolls says "If the spell is on your class's list you can use an action to read the scroll [...] Otherwise, the scroll is unintelligible".

Basically, if you can read you can use a scroll (ex: Scroll of Protection, DMG 199), but only if the spell is on your list you can use an Spell Scroll (DMG 200).

A even more specific exception to this rule is the Use Magic Device feature of the 13th-level Thief (Roguish Archetype): "You ignore all class, race, and level requirements on the use of magic items." Jeremy Crawford tweeted "The intent is that Use Magic Device does allow a rogue to try to use a scroll." Since everyone can use a normal scroll, he meant the use of a Spell Scroll.