Its not a huge deal I just take it kind of offensive when some player think they NEED a prestige class to have a character be something. The core rules are in my opinion more than enough.
Sometimes they aren't. A nimble, swashbuckling combatant is going to be lame as a core fighter or a fighter/rogue; he pretty much needs to be a duelist and/or swashbuckler to compete with a standard fighter. (Which is pretty sad, since the standard fighter is one of the weaker core classes). A multiclassed caster is usually bad enough with
the prestige classes (arcane trickster, eldritch knight, mystic theurge) that make them usable. There are plenty of concepts that can't be executed with the core classes without kneecapping yourself.
But you have to admit there are WAY TOO many books for someone to know all the rules and many like the Unearthed Arcana are supposed to be optional.
I'll grant that I don't know all
the rules, and it can be hard to keep up, but I'm doing pretty well so far.
So without a HUGE STACK OF BOOKS how can I do a character as good as yours?
You already have. Your character, as a 10th-level wizard equivalent, is certainly more powerful than mine.