Estimate cost to start a new hobby.
Starting a hobby has an entry cost and a running cost, and the sensible way to judge it is the blended monthly figure over a realistic trial period. Second-hand buying is modelled at roughly 55% of retail applied to the share you buy used, which is what the market actually bears for lightly used equipment across most hobbies. The practical implication is that the optional gear line is the one to defer: buy essentials, take the introductory course, and let three months of actual use tell you whether the upgrades are worth buying at all.
Cost to start a hobby
Gear = retail x (1 - second-hand share x 0.45); total = gear + tuition + monthly consumables x months; per month = total / months
Three to six months. It is long enough to pass the initial enthusiasm and see whether the hobby survives contact with a busy week, and short enough that the committed spend stays modest.
For most hobbies yes, and the resale market is the reason: buying used means losing very little if you stop, whereas new equipment loses roughly 45% the moment it is used. The exceptions are safety equipment and anything sized to the individual.
Because until you have used the essentials you cannot tell which upgrades address a real constraint. Most abandoned hobbies are abandoned with the upgrade gear barely used, and that is the avoidable part of the loss.