$100K by the age of 30?

Today the Straits Times has an article showing that it is possible to save $100k with roughly 6 years of work.

The article showed that it is possible with a starting salary of $3,050, 15 months salary a year (3 months bonus), pay rise 4.5% a year and saving rate of 50% your annual pay.

For curiosity's sake, I ran a calculation with the following assumptions:
1. Starting pay $2,550,
2. 1.5 months bonus every year,
3. 4% pay increment every year,
4. Saving rate 50% of pay,
5. 40% of saving at bank generating 1% interest,
6. 60% of saving on investments with 4% returns (e.g. dividends from stocks).

Age	Monthly Pay	TakeHome Pay	Annual Pay	Save 50%	40% at bank	60% invest	Total Savings
25	2550	2040	27540	13770	5563	8592	14156
26	2652	2122	28642	14321	11404	17872	29277
27	2758	2206	29787	14894	17535	27881	45416
28	2868	2295	30979	15489	23968	38661	62630
29	2983	2387	32218	16109	30716	50260	80976
30	3102	2482	33507	16753	37792	62724	100516

Therefore, we can just about making $100K even with my above assumptions.

However, great sacrifices must be made:
1. Work near your home, so as to minimize transportation cost.
2. Absolutely "No-no" owning a car.
3. Pack your own lunch to office, minimize eating out.
4. Do not indulge in expensive hobbies.
5. No branded or luxurious possessions.
6. No housing, wedding, honeymoon, children, medical, etc, commitments.

Besides these massive sacrifices, also:
1. No market crash during these six years, 
2. No fatal investment mistake.

So, do we want delayed gratification or eating our marshmallow immediately?