Collecting 1 Bitcoin is like collecting any other amount of money.  Both deserve a job and make an effort and get paid for it.  Maybe the easiest way to do this is to invest successfully in a specific project, but it is not easy to identify these successful projects or to distinguish them among the thousands of investment opportunities in the market.  This would be a kind of gambling, but with better guarantees, perhaps. 
I do not know for how long you want to collect this amount, but logically the amount is relatively large and it will take some time to collect it, whatever method you adopt. 
I think it is better to move this topic to the beginners section, because that is the best place for such questions.

Do you mean free geniun way of collecting of 1BTC or using your money ?
If you mean free method then there are some legit site that you do some tasks and you get rewarded in BTC.

Then if it's investment wise you're talking about, then you have to first identify how much you can afford to loose from your earnings if you have one, Then invest using dollar cost averaging (DCA) on weekly, monthly basis or whichever way that suits you since you've understood that is not an overnight something, good.

With this method I do believe you will one day achieve the goal of owing 1 BTC no matter how long that it will take you.

Then the best option is DCA. Every month at payday you buy a certain amount of BTC, depending on what you can afford.
Plus, if you get some extra work in your free time - no matter it pays in fiat and you also convert that fiat into bitcoin, or it pays in bitcoin, or it pays in altcoins (just make sure you accept only altcoins that are actively traded) and you convert - that's a nice bonus.

If you are too young and you don't have a job yet, I advise you learn as much and as good as possible and don't spend all your time chasing bitcoin. Maybe only parts of it though

1BTC is a huge milestone to achieve on the current especially if you have no decent job to sustain your continuous savings. And also it’s not a must to have 1BTC as target because everyone can start small @ 1mbtc and just increase once you achieve it. Having a different level of achievement is more encouraging rather than setting the bar high even if its too unrealistic for your current financial status.

My target before when I’m newbie was 0.1BTC when Bitcoin is still around 300$ then later on I manage to accumulate 1BTC after I get my first job and purchased Bitcoin using half of my salary. My target increase that time as I progress on achieving round number amount until I cash out my Bitcoin to purchase my house on 20K and maintain an amount that I’m contented in fiat not in BTC.

You're not really need to join 1 BTC club if you want to get huge money, even you hold 0.5 BTC or less but you're keep holding until Bitcoin make new ATH, you will get a lot profit in USD equivalent. But if you can achieve 1 BTC of course it's a milestone since not many people can achieve that. Rather than asking the solution from other users, I think you're already know how to that? Yes, get a job, get a high salary job.

Investing is good, money management is important, but if you didn't get a job to make money, you can't invest and manage your money!

At the current normal payrate of 0.0025 Bitcoin per week you will get one Bitcoin after 400 Weeks. If you consider that you need to find new campaigns form time to time you will end up with around 10 years of basically non stop signature campaigns to archive 1 Bitcoin. Sounds a lot and not doable, yet I#m already more than 9 years on bitcointalk, so a good time to start now with the campaigns 

Any amount of Bitcoin would do; not necessarily 1 BTC in a bang, but ofcourse the bigger the investment, the bigger the profit will also be but that would also enlarge the risk given that the market price is volatile. If it is a way to have 1 BYC, buy it if you can 'coz earning it, as OP have mentioned would take that long. There are ways to earn BTC and those were discussed numerous times already in this forum; you may join campaigns, participate on air drops and also, contests (editting, art related, etc.)
If you'd solely depend on the campaign payments, ofcourse that would be hard. But try reinvesting what you have earned from projects to somehow help the progress of having a bigger capital to invest. Earned rewards from campaigns could be invested to profitable tokens. You may engage to trading if you have the knowledge. Or anything which could help you earn more, that's just the point.

This is one of the most straight to the point post I've ever seen on the forum.
You should know that just as you stated that not by magic and now you started mentioning gambling and the rest as what will fetch you 1btc ? Wow I'm shocked.
It seems you have to stop referring to it as 1 Bitcoin and start adding the monetary value to it while talking about it.

Get your capital to invest into bitcoin by any legal means including gambling but don't lend money to invest, then try to learn a specific pattern to engage with your bitcoin depending on your plan, if you're going on a long term investment with bitcoin then you can hodl your coins but if it's a short time running is what you intended, learning to trade will be profitable to you as well including all the types and make your returns from every sale after purchase bit yoi will need to learn this pattern together with DCA.