I'd rather Die looking cool than live looking like a ****.
You beat me to it. Except I'd say I'd rather look like a tool and live than look cool and die!
In winter I wear an extra hi vis vest over my Buffalo jacket all the time. In summer I used to have a lightweight hi vis but it broke. Now I just rely on the hi vis on the jacket.
Essentially, your Dad is a smart man. You can also negate it by getting a cool looking jacket with it all built in, rather than one that looks like a building site bog standard hivis jacket.
You would also be surprised. I see A LOT of bikers wearing hi-vis, except power rangers and hog riders. (Everyone in between pretty much).
You sound quite young and inexperienced, correct me/apologies if I am wrong. If this is the case, get hi vis!!!!!!!!!! Please do not take a gamble on a being seen without hi vis for the sake of looking cool/saving money.
Is your life worth risking to look cool over?
Also, as above, get a decent helmet. I've seen a hi vis (yellow) looking helmet before. Quirky as hell but no one could EVER argue they didn't see him. A white one will do a good job too!