I started with at about 7ish with a little penknife with a fake staghorn handle that I found and hid from my parents.
I probably bought my first purchased folding knife (plastic scales with a little metal shield design) about age 9 and still remember using it in class at school to sharpen pencils 'cos sharpeners were for rich kids. How times have changed.
When I was 11 or 12 I hit paydirt. My older brother had a bit of a secret knife collection which my mother found and promptly confiscated before putting it in the bin outside. I found them when taking out the rubbish so naturally recovered them but somehow completely forgot to tell my brother
. There was a Sykes Fairbairn copy, a Scout sheath knife, a few locknives, a bowie knife as well as a couple of throwing knives. I did however own up to him, albeit a few years later.
About 13-14 I bought a horrendous cheap brown plastic handled multiblade folding knife for Scout camps which had a knife and spoon attached jutting out so awkwardly that the knife couldn't really be used for anything apart from shovelling food into your gob, even then you risked serious injury because of all the pokey-out bits. I ended up taking the cutlery off with a hacksaw after which it wouldn't close properly.
Shortly after I bought a "Crocodile Hunter"...around the time of the first Crocodile Dundee film if I remember. I was a bowie style knife but ridiculously large, obviously so owners could produce it and and confidently utter
"Nah mate, this is a KNIFE!"
My next knife was identical to Johnathan's below when I was 16 or so...lots of fun to be had with the slingshot but never yet had call to use the harpoon
I've still got it and recently passed it onto my youngest son as his own knife when I decided he was using one safely and sensibly. He was the first of my kids to own their own knife and as the youngest it was recognising the fact that maturity isn't just about age. He uses it when we're camping or out bushcrafting but the rest of the time it's locked away with the other kit.
In my late teens/early twenties most of my bladed stuff was martial arts related but also had an axe my uncle gave me as a gift (he made me give him a silver coin, a tradition I've continued with). My father borrowed it and I never saw it again until last year when I found it rusting in his garage I've since renovated it but may need to fit a new handle as I'm dubious about the handle and not wiling to risk it breaking in use.
Later 20's, early 30's I bought my first parang/machette/bolo type thingy
(it didn't fit neatly into any category). It was also cheap cack and broke at the handle as despite having a thick blade that looked like like it could fell an oak tree, it had a skinny little tang that didn't stand up to it's first use.
Later 30's I bought a decent cold steel copy that IIRC was described as a bolo smachette? It served me well until I lost it for a few years
(well couldn't find it...until of course a few days after I bought a new one...it had fallen down the back of a shelving unit where I store camping gear/rucksacks)
Last few knives were bought over the past 4-5 years. Various locknives...one for climbing, one for fishing, one multitool for the car, one for my walking rucksack. Last year I bought a Jack Pyke bushcraft knife which is solid enough for my needs until I win the lottery and can buy one of each of the lovely custom made knives I see on here as they are all stunning shiny kit and works of art. .
My little gerber locknife that lives next to my computer that's used for everyday stuff like opening letters, parcels, cutting rope/paracord is my main tool.